Impact of Preseason Climate Factors on Vegetation Photosynthetic Phenology in Mid-High Latitudes of the Northern Hemisphere.

During the period preceding the vegetation growing season (GS), temperature emerges as the pivotal factor determining phenology in northern terrestrial ecosystems. Despite extensive research on the impact of daily mean temperature (Tmean) during the preseason period, the influence of diurnal temperature range (DTR) on vegetation photosynthetic phenology (i.e., the impact of the plant photosynthetic cycle on seasonal time scale) has largely been neglected. Using a long-term vegetation photosynthetic phenology dataset and historical climate data, we examine vegetation photosynthetic phenology dynamics and responses to climate change across the mid-high latitudes of the Northern Hemisphere from 2001 to 2020. Our data reveal an advancing trend in the start of the GS (SOS) by -0.15 days per year (days yr-1), affecting 72.1% of the studied area. This is particularly pronounced in western Canada, Alaska, eastern Asia, and latitudes north of 60°N. Conversely, the end of the GS (EOS) displays a delaying trend of 0.17 days yr-1, impacting 62.4% of the studied area, especially northern North America and northern Eurasia. The collective influence of an earlier SOS and a delayed EOS has resulted in the notably prolonged length of the GS (LOS) by 0.32 days yr-1 in the last two decades, affecting 70.9% of the studied area, with Eurasia and western North America being particularly noteworthy. Partial correlation coefficients of the SOS with preseason Tmean, DTR, and accumulated precipitation exhibited negative values in 98.4%, 93.0%, and 39.2% of the study area, respectively. However, there were distinct regional variations in the influence of climate factors on the EOS. The partial correlation coefficients of the EOS with preseason Tmean, DTR, and precipitation were positive in 58.6%, 50.1%, and 36.3% of the region, respectively. Our findings unveil the intricate mechanisms influencing vegetation photosynthetic phenology, holding crucial significance in understanding the dynamics of carbon sequestration within terrestrial ecosystems amidst climate change.

Effect of inflammatory response on joint function after hip fracture in elderly patients: A clinical study.

BACKGROUND: Excellent hip joint function facilitates limb recovery and improves the quality of survival. This study aimed to investigate the potential risk factors affecting postoperative joint functional activity and outcomes in elderly hip fractures patients and to provide evidence for patient rehabilitation and clinical management. AIM: To explore the relationship between inflammatory factors and hip function and the interaction between inflammation and health after hip fracture in elderly patients. METHODS: The elderly patients who had hip fracture surgery at our hospital between January 1, 2021, and December 31, 2022 were chosen for this retrospective clinical investigation. Patients with excellent and fair postoperative hip function had their clinical information and characteristics gathered and compared. Age, gender, fracture site, surgical technique, laboratory indices, and other variables that could have an impact on postoperative joint function were all included in a univariate study. To further identify independent risk factors affecting postoperative joint function in hip fractures, risk factors that showed statistical significance in the univariate analysis were then included in a multiple logistic regression analysis. In addition to this, we also compared other outcome variables such as visual analogue scale and length of hospital stay between the two groups. RESULTS: A total of 119 elderly patients with hip fractures were included in this study, of whom 37 were male and 82 were female. The results of univariate logistic regression analysis after excluding the interaction of various factors showed that there was a statistically significant difference in interleukin (IL)-6, IL-8, IL-10, C-reactive protein (CRP), and complement C1q (C1q) between the fair and excellent joint function groups (P < 0.05). The results of multiple logistic regression analysis showed that IL-6 > 20 pg/mL [(Odds ratio (OR) 3.070, 95%CI: 1.243-7.579], IL-8 > 21.4 pg/ mL (OR 3.827, 95%CI: 1.498-9.773), CRP > 10 mg/L (OR 2.142, 95%CI: 1.020-4.498) and C1q > 233 mg/L (OR 2.339, 95%CI: 1.094-5.004) were independent risk factors for poor joint function after hip fracture surgery (all P < 0.05). CONCLUSION: After hip fractures in older patients, inflammatory variables are risk factors for fair joint function; therefore, early intervention to address these markers is essential to enhance joint function and avoid consequences.

Comprehensive evaluation framework for intervention on health effects of ambient temperature.

Despite the existence of many interventions to mitigate or adapt to the health effects of climate change, their effectiveness remains unclear. Here, we introduce the Comprehensive Evaluation Framework for Intervention on Health Effects of Ambient Temperature to evaluate study designs and effects of intervention studies. The framework comprises three types of interventions: proactive, indirect, and direct, and four categories of indicators: classification, methods, scope, and effects. We trialed the framework by an evaluation of existing intervention studies. The evaluation revealed that each intervention has its own applicable characteristics in terms of effectiveness, feasibility, and generalizability scores. We expanded the framework's potential by offering a list of intervention recommendations in different scenarios. Future applications are then explored to establish models of the relationship between study designs and intervention effects, facilitating effective interventions to address the health effects of ambient temperature under climate change.

Bias distribution and regulation in photoelectrochemical overall water-splitting cells.

The water oxidation half-reaction at anodes is always considered the rate-limiting step of overall water splitting (OWS), but the actual bias distribution between photoanodes and cathodes of photoelectrochemical (PEC) OWS cells has not been investigated systematically. In this work, we find that, for PEC cells consisting of photoanodes (nickel-modified n-Si [Ni/n-Si] and α-Fe2O3) with low photovoltage (Vph < 1 V), a large portion of applied bias is exerted on the Pt cathode for satisfying the hydrogen evolution thermodynamics, showing a thermodynamics-controlled characteristic. In contrast, for photoanodes (TiO2 and BiVO4) with Vph > 1 V, the bias required for cathode activation can be significantly reduced, exhibiting a kinetics-controlled characteristic. Further investigations show that the bias distribution can be regulated by tuning the electrolyte pH and using alternative half-reaction couplings. Accordingly, a volcano plot is presented for the rational design of the overall reactions and unbiased PEC cells. Motivated by this, an unbiased PEC cell consisting of a simple Ni/n-Si photoanode and Pt cathode is assembled, delivering a photocurrent density of 5.3 ± 0.2 mA cm-2.

Producing high-quantity and high-quality recombinant adeno-associated virus by low-cis triple transfection.

Recombinant adeno-associated virus (rAAV)-based gene therapy is entering clinical and commercial stages at an unprecedented pace. Triple transfection of HEK293 cells is currently the most widely used platform for rAAV manufacturing. Here, we develop low-cis triple transfection that decreases transgene plasmid use by 10- to 100-fold and overcomes several major limitations associated with standard triple transfection. This new method improves packaging of yield-inhibiting transgenes by up to 10-fold, and generates rAAV batches with reduced plasmid backbone contamination that otherwise cannot be eliminated in downstream processing. When tested in mice and compared with rAAV produced by standard triple transfection, low-cis rAAV shows comparable or superior potency and results in diminished plasmid backbone DNA and RNA persistence in tissue. Mechanistically, low-cis triple transfection relies on the extensive replication of transgene cassette (i.e., inverted terminal repeat-flanked vector DNA) in HEK293 cells during production phase. This cost-effective method can be easily implemented and is widely applicable to producing rAAV of high quantity, purity, and potency.

B Cells and IL-21-Producing Follicular Helper T Cells Cooperate to Determine the Dynamic Alterations of Premetastatic Tumor Draining Lymph Nodes of Breast Cancer.

Metastasis is the major cause of cancer-related death, and lymph node is the most common site of metastasis in breast cancer. However, the alterations that happen in tumor-draining lymph nodes (TDLNs) to form a premetastatic microenvironment are largely unknown. Here, we first report the dynamic changes in size and immune status of TDLNs before metastasis in breast cancer. With the progression of tumor, the TDLN is first enlarged and immune-activated at early stage that contains specific antitumor immunity against metastasis. The TDLN is then contracted and immunosuppressed at late stage before finally getting metastasized. Mechanistically, B and follicular helper T (Tfh) cells parallelly expand and contract to determine the size of TDLN. The activation status and specific antitumor immunity of CD8+ T cells in the TDLN are determined by interleukin-21 (IL-21) produced by Tfh cells, thus showing parallel changes. The turn from activated enlargement to suppressed contraction is due to the spontaneous contraction of germinal centers mediated by follicular regulatory T cells. On the basis of the B-Tfh-IL-21-CD8+ T cell axis, we prove that targeting the axis could activate TDLNs to resist metastasis. Together, our findings identify the dynamic alterations and regulatory mechanisms of premetastatic TDLNs of breast cancer and provide new strategies to inhibit lymph node metastasis.

Harnessing Renewable Lignocellulosic Potential for Sustainable Wastewater Purification.

Utilizing renewable lignocellulosic resources for wastewater remediation is crucial to achieving sustainable social development. However, the resulting by-products and the synthetic process characterized by complexity, high cost, and environmental pollution limit the further development of lignocellulose-based materials. Here, we developed a sustainable strategy that involved a new functional deep eutectic solvent (DES) to deconstruct industrial xylose residue into cellulose-rich residue with carboxyl groups, lignin with carboxyl and quaternary ammonium salt groups, and DES effluent rich in lignin fragments. Subsequently, these fractions equipped with customized functionality were used to produce efficient wastewater remediation materials in cost-effective and environmentally sound manners, namely, photocatalyst prepared by carboxyl-modified cellulose residue, biochar-based adsorbent originated from modified lignin, and flocculant synthesized by self-catalytic in situ copolymerization of residual DES effluent at room temperature. Under the no-waste principle, this strategy upgraded the whole components of waste lignocellulose into high-value-added wastewater remediation materials with excellent universality. These materials in coordination with each other can stepwise purify high-hazardous mineral processing wastewater into drinkable water, including the removal of 99.81% of suspended solids, almost all various heavy metal ions, and 97.09% chemical oxygen demand, respectively. This work provided promising solutions and blueprints for lignocellulosic resources to alleviate water shortages while also advancing the global goal of carbon neutrality.

Cancer on motors: How kinesins drive prostate cancer progression?

Prostate cancer causes numerous male deaths annually. Although great progress has been made in the diagnosis and treatment of prostate cancer during the past several decades, much about this disease remains unknown, especially its pathobiology. The kinesin superfamily is a pivotal group of motor proteins, that contains a microtubule-based motor domain and features an adenosine triphosphatase activity and motility characteristics. Large-scale sequencing analyses based on clinical samples and animal models have shown that several members of the kinesin family are dysregulated in prostate cancer. Abnormal expression of kinesins could be linked to uncontrolled cell growth, inhibited apoptosis and increased metastasis ability. Additionally, kinesins may be implicated in chemotherapy resistance and escape immunologic cytotoxicity, which creates a barrier to cancer treatment. Here we cover the recent advances in understanding how kinesins may drive prostate cancer progression and how targeting their function may be a therapeutic strategy. A better understanding of kinesins in prostate cancer tumorigenesis may be pivotal for improving disease outcomes in prostate cancer patients.

Effects of polymerization types on plastics ingestion and biodegradation by Zophobas atratus larvae, and successions of both gut bacterial and fungal microbiomes.

Recent studies demonstrated that plastic degradation in Zophobas atratus superworms is related to the gut microbiota. To determine whether the biodegradation and gut-microbiota were influenced by ingested plastic polymerization types, foams of polypropylene (PP), polyurethane (PU) and ethylene vinyl acetate (EVA) were selected as representatives of polyolefins, polyester and copolymers, and the sole feedstock for superworms for 45 d. Both growth and survival rates of superworms were influenced by the type of plastic diet. Although the total consumptions of EVA- and PP-fed groups were similar at 29.03 ± 0.93 and 28.89 ± 1.14 mg/g-larva, which were both significantly higher than that of PU-fed groups (21.63 ± 2.18 mg/g-larva), the final survival rates of the EVA-fed group of 36.67 ± 10.41% exhibited significantly lower than that of the PP- and PU-fed groups of 76.67 ± 2.89% and 75.00 ± 7.07%, respectively, and even the starvation group of 51.67 ± 10.93%. The Illumina MiSeq results revealed similarities in the dominant gut bacterial communities between PU- and EVA-fed groups, with an increase in relative abundance of Lactococcus, but significant differences from the PP-fed groups, which had two predominant genera of unclassified Enterobacteriaceae and Enterococcus. Compared to bran-fed groups, changes in gut fungal communities were similar across all plastics-fed groups, with an increase in the dominant abundance of Rhodotorula. The abundance of Rhodotorula increased in the order of polyolefin, polyester, and copolymer. In summary, plastic ingestion, larval growth, and changes in gut bacterial and fungal community of superworms were all influenced by foam diets of different polymerization types, and especially influences on the gut microbiomes were different from each other.

Analysis of the impact of radiotherapy and surgical treatment regimens based on the SEER database on the survival outcomes of rectal cancer patients over 70 years.

OBJECTIVE: This study evaluates the impact of different combinations of treatment regimens, such as additional radiation, chemotherapy, and surgical treatments, on the survival of elderly rectal cancer patients ≥ 70 years of age to support physicians' clinical decision-making. METHODS: Data from a sample of elderly rectal cancer patients aged ≥ 70 years diagnosed from 2005-2015 from the US surveillance, epidemiology, and end results (SEER) database were retrospectively analyzed. The best cut-off point was selected using the x-tile software for the three continuity indices: age, tumor size, and number of regional lymph nodes. All patients were categorized into either the neoadjuvant radiotherapy and surgery group (R_S group), the surgical treatment group (S group), or the surgery and adjuvant radiotherapy group (S_R group). The propensity score allocation was used to match each included study subject in a 1:1 ratio, and the restricted mean survival time method (RMST) was used to predict the mean survival of rectal cancer patients within 5 and 10 years. The prognostic risk factors for rectal cancer patients were determined using univariate and multivariate Cox regression analyses, and nomograms were constructed. A subgroup stratification analysis of patients with different treatment combination regimens was performed using the Kaplan-Meier method, and log-rank tests were used for between-group comparisons. The model's predictive accuracy was assessed by receiver operating characteristic (ROC) curves, correction curves, and a clinical decision curve analysis (DCA). RESULTS: A total of 7556 cases of sample data from 2005 to 2015 were included, which were categorized into 6639 patients (87.86%) in the S group, 408 patients (5.4%) in the R_S group, and 509 patients (6.74%) in the S_R group, according to the relevant order of radiotherapy and surgery. After propensity score matching (PSM), the primary clinical characteristics of the groups were balanced and comparable. The difference in the mean survival time before and after PSM was not statistically significant in both R_S and S groups (P value > 0.05), and the difference in the mean survival time after PSM was statistically substantial in S_R and S groups (P value < 0.05). In the multifactorial Cox analysis, the M1 stage and Nodes ≥ 9 were independent risk factors. An age between 70-75 was an independent protective factor for patients with rectal cancer in the R_S and S groups. The Marital_status, T4 stage, N2 stage, M1 stage, and Nodes ≥ 9 were independent risk factors for patients with rectal cancer in the S_R and S groups, and an age between 70-81 was an independent protective factor. The ROC curve area, the model C index, and the survival calibration curve suggested good agreement between the actual and predicted values of the model. The DCA for 3-year, 5-year, and 10-year survival periods indicated that the model had some potential for application. CONCLUSIONS: The results of the study showed no significant difference in the overall survival (OS) between elderly patients who received neoadjuvant radiotherapy and surgery and those who received surgery alone; elderly patients who received surgery and adjuvant radiotherapy had some survival benefits compared with those who received surgery alone, though the benefit of adjuvant radiotherapy was not significant. Therefore, radiotherapy for rectal cancer patients older than 70 years old should be based on individual differences in condition, and a precise treatment plan should be developed.

The tumor niche can reprogram long-lived protumorigenic neutrophils.

The heterogeneity and plasticity of neutrophils in tumor-host interactions and how tumor signals induce reprogramming of neutrophil subpopulations need further investigation. Ng et al. recently reported that a hypoxic-glycolytic niche in mouse tumors could reprogram mature and immature neutrophils into a long-lived and terminally-differentiated subset, which promoted angiogenesis and tumor growth.

Distribution patterns and influential factors of pathogenic bacteria in freshwater aquaculture sediments.

Pathogenic bacteria, the major causative agents of aquaculture diseases, are a serious impediment to the aquaculture industry. However, the bioinformatics of pathogenic bacteria and virulence factors (VFs) in sediments, an important component of freshwater aquaculture ecosystems, are not well characterized. In this study, 20 sediment samples were collected from fish pond sediments (FPS), shrimp field sediments (SFS), fish pond sediment control (FPSC), and shrimp field sediment control (SFSC). Molecular biological information was obtained on a total of 173 pathogenic bacteria, 1093 virulence factors (VFs), and 8475 mobile genetic elements (MGEs) from these samples. The results indicated that (1) aquaculture patterns and sediment characteristics can affect the distribution of pathogenic bacteria. According to the results of the Kruskal-Wallis H test, except for Mycobacterium gilvum, there were significant differences (P < 0.05) among the four sediment types in the average abundance of major pathogenic bacteria (top 30 in abundance), and the average abundance of major pathogenic bacteria in the four sediment types followed the following pattern: FPS > SFS > FPSC > SFSC. (2) Pathogenic bacteria are able to implement a variety of complex pathogenic mechanisms such as adhesion, invasion, immune evasion, and metabolic regulation in the host because they carry a variety of VFs such as type IV pili, HSI-I, Alginate, Colibactin, and Capsule. According to the primary classification of the Virulence Factor Database (VFDB), the abundance of VFs in all four types of sediments showed the following pattern: offensive VFs > non-specific VFs > defensive VFs > regulation of virulence-related genes. (3) Total organic carbon (TOC), total phosphorus (TP), available phosphorus (AP), nitrite, and nitrate were mostly only weakly positively correlated with the major pathogenic bacteria and could promote the growth of pathogenic bacteria to some extent, whereas ammonia was significantly positively correlated with most of the major pathogenic bacteria and could play an important role in promoting the growth and reproduction of pathogenic bacteria. (4) Meanwhile, there was also a significant positive correlation between CAZyme genes and major pathogenic bacteria (0.62 ≤ R ≤ 0.89, P < 0.05). This suggests that these pathogenic bacteria could be the main carriers of CAZyme genes and, to some extent, gained a higher level of metabolic activity by degrading organic matter in the sediments to maintain their competitive advantage. (5) Worryingly, the results of correlation analyses indicated that MGEs in aquaculture sediments could play an important role in the spread of VFs (R = 0.82, P < 0.01), and in particular, plasmids (R = 0.75, P < 0.01) and integrative and conjugative elements (ICEs, R = 0.65, P < 0.05) could be these major vectors of VFs. The results of this study contribute to a comprehensive understanding of the health of freshwater aquaculture sediments and provide a scientific basis for aquaculture management and conservation.

Dialysis bag-microalgae photobioreactor: Novel strategy for enhanced bioresource production and wastewater purification.

Cultivating microalgae in wastewater offers various advantages, but it still faces limitations such as bacteria and other impurities in wastewater affecting the growth and purity of microalgae, difficulty in microalgae harvesting, and extracellular products of microalgae affecting effluent quality. In this study, a novel dialysis bag-microalgae photobioreactor (Db-PBR) was developed to achieve wastewater purification and purer bioresource recovery by culturing microalgae in a dialysis bag. The dialysis bag in the Db-PBR effectively captured the microalgae cells and promoted their lipid accumulation, leading to higher biomass (1.53 times of the control) and lipid production (2.50 times of the control). During the stable operation stage of Db-PBR, the average soluble microbial products (SMP) content outside the dialysis bag was 25.83 mg L-1, which was significantly lower than that inside the dialysis bag (185.63 mg L-1), indicating that the dialysis bag effectively intercepted the SMP secreted by microalgae. As a result, the concentration of dissolved organic carbon (DOC) in Db-PBR effluent was significantly lower than that of traditional photobioreactor. Furthermore, benefiting from the dialysis bag in the reactor effectively intercepted the microorganisms in wastewater, significantly improving the purity of the cultured microalgae biomass, which is beneficial for the development of high-value microalgae products.

Methanol as an anti-solvent to improve the low open-circuit voltage of CsPbBr3 perovskite solar cells prepared with water.

CsPbBr3 has received more and more attention in the field of optoelectronic devices due to its excellent stability. To address the cost and environmental concerns associated with the use of toxic methanol, water has been explored as a substitute solvent for CsBr in the preparation of CsPbBr3 perovskite solar cells (PSCs). In this study, we utilized methanol as an anti-solvent of the CsBr/H2O solution to regulate the detrimental effects of water on the CsPbBr3 film and control the crystallization process. From results of the experiment, it was found that methanol anti-solvent treatment greatly improved the crystallization of the CsPbBr3 film, increased the grain size, and reduced the defect density. After the introduction of methanol anti-solvent treatment, the power conversion efficiency (PCE) increased from 6.09% to 7.91%, while the open-circuit voltage (Voc) increased from 1.18 V to 1.39 V. Furthermore, we incorporated 2-hydroxyethylurea into the CsPbBr3 PSCs to improve the wettability of PbBr2 towards the CsBr/H2O solution and ensure the formation of pure-phase CsPbBr3 films. The introduction of 2-hydroxyethylurea resulted in an additional increase in Voc from 1.19 V to 1.42 V. The PCE further improved from 6.56% to 8.62% after methanol anti-solvent treatment. These results demonstrate that methanol treatment effectively addresses the low Voc issue observed in CsPbBr3 PSCs prepared with water as a solvent. Importantly, this approach significantly reduces the reliance on methanol compared to conventional fabrication methods for CsPbBr3 PSCs. Overall, this work presents a promising pathway for achieving high Voc and efficiency in CsPbBr3 PSCs by utilizing water as a solvent.

Facile preparation of low temperature carbon dots with long-wavelength emission and their sensing applications for crystal violet.

Crystal violet (CV) is one of the main components of common fungicides in daily life, which has inhibitory effect on gram-positive bacteria. However, CV remains in the environment for a long time and have potential risk of disease. Therefore, it is necessary to develop effective methods for detecting CV. Low-temperature carbon dots (LT-CDs) are studied to provide a new idea for the development of CDs green preparation technology from the perspective of low energy consumption. In this experiment, LT-CDs with long-wavelength emission were prepared based on the oxidation, cross-linking polymerization and Schiff base reaction using o-phenylenediamine and hydroquinone as carbon source at low temperature, and were characterized by various techniques. It was found that LT-CDs could be used as a fluorescent probe for quantitative detection of CV based on the inner filter effect, and the practicability of the method was verified by real samples.

Biomaterials for bone defect repair: Types, mechanisms and effects.

Bone defects or bone discontinuities caused by trauma, infection, tumours and other diseases have led to an increasing demand for bone grafts and biomaterials. Autologous bone grafts, bone grafts with vascular tips, anastomosed vascular bone grafts and autologous bone marrow components are all commonly used in clinical practice, while oversized bone defects require the use of bone tissue engineering-related biomaterials to repair bone defects and promote bone regeneration. Currently, inorganic components such as polysaccharides and bioceramics, as well as a variety of bioactive proteins, metal ions and stem cells can be loaded into hydrogels or 3D printed scaffold materials to achieve better therapeutic results. In this review, we provide an overview of the types of materials, applications, potential mechanisms and current developments in the repair of bone defects.

Exosomes derived from cancer-associated fibroblasts promote tumorigenesis, metastasis and chemoresistance of colorectal cancer by upregulating circ_0067557 to target Lin28.

BACKGROUND: Cancer associated fibroblasts (CAFs) can remodel tumor microenvironment by secreting exosomes. This study aimed to investigate the role of exosomes derived from cancer-associated fibroblasts in colorectal cancer (CRC) progression. METHODS: Circular RNA (circRNA) array was used to identify differentially expressed circRNAs in exosomes from normal fibroblasts (NFs) and CAFs, and confirmed one differentially expressed circRNA circ_0067557 by real-time PCR. The effect of circ_0067557 on proliferation, metastasis, chemoresistance and apoptosis was verified by wound heal, tranwell, CCK8, sphere-forming and flow cytometry assay. RESULTS: Circ_0067557 expression in exosomes from CAFs was higher than those from NFs. CAF-derived exosomes promoted the proliferation, migration, invasion and chemoresistance of CRC cells while suppressed apoptosis. Silencing of circ_0067557 inhibited malignant phenotypes of CRC cells by targeting Lin28A and Lin28B. Moreover, CAF-derived exosomes enhanced the growth of CRC xenograft tumors. CONCLUSION: Circ_0067557/Lin28A and Lin28B signal axis may be a potential therapy target for CRC.

N-Heterocyclic Carbene-Catalyzed Highly Enantioselective Macrolactonization to Access Planar-Chiral Macrocycles.

An N-heterocyclic carbene (NHC)-catalyzed atroposelective macrolactonization has been disclosed. This approach affords planar-chiral macrocycles in high yields with excellent enantioselectivities over a broad substrate scope. Controlled experiments suggest that the enantioselectivity might arise from the cation-n interaction between the acyl azolium and the electron-rich moiety in the substrate. This mechanism is supported by density functional theory calculations, which also suggest an important π-π interaction in stabilizing the transition state.

A Practical Framework for Novel Electronic Nicotine Delivery System Evaluation: Chemical and Toxicological Characterization of JUUL2 Aerosol and Comparison with Reference Cigarettes.

Electronic nicotine delivery systems (ENDSs) are designed as a non-combustible alternative to cigarettes, aiming to deliver nicotine without the harmful byproducts of tobacco combustion. As the category evolves and new ENDS products emerge, it is important to continually assess the levels of toxicologically relevant chemicals in the aerosols and characterize any related toxicology. Herein, we present a proposed framework for characterizing novel ENDS products (i.e., devices and formulations) and determining the reduced risk potential utilizing analytical chemistry and in vitro toxicological studies with a qualitative risk assessment. To demonstrate this proposed framework, long-term stability studies (12 months) analyzing relevant toxicant emissions from six formulations of a next-generation product, JUUL2, were conducted and compared to reference combustible cigarette (CC) smoke under both non-intense and intense puffing regimes. In addition, in vitro cytotoxicity, mutagenicity, and genotoxicity assays were conducted on aerosol and smoke condensates. In all samples, relevant toxicants under both non-intense and intense puffing regimes were substantially lower than those observed in reference CC smoke. Furthermore, neither cytotoxicity, mutagenicity, nor genotoxicity was observed in aerosol condensates generated under both intense and non-intense puffing regimes, in contrast to results observed for reference cigarettes. Following the proposed framework, the results demonstrate that the ENDS products studied in this work generate significantly lower levels of toxicants relative to reference cigarettes and were not cytotoxic, mutagenic, or genotoxic under these in vitro assay conditions.