Unbound Fractions of PFAS in Human and Rodent Tissues: Rat Liver a Suitable Proxy for Evaluating Emerging PFAS?

Adverse health effects associated with exposures to perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a concern for public health and are driven by their elimination half-lives and accumulation in specific tissues. However, data on PFAS binding in human tissues are limited. Accumulation of PFAS in human tissues has been linked to interactions with specific proteins and lipids in target organs. Additional data on PFAS binding and unbound fractions (funbound) in whole human tissues are urgently needed. Here, we address this gap by using rapid equilibrium dialysis to measure the binding and funbound of 16 PFAS with 3 to 13 perfluorinated carbon atoms (ηpfc = 3-13) and several functional headgroups in human liver, lung, kidney, heart, and brain tissue. We compare results to mouse (C57BL/6 and CD-1) and rat tissues. Results show that funbound decreases with increasing fluorinated carbon chain length and hydrophobicity. Among human tissues, PFAS binding was generally greatest in brain > liver ≈ kidneys ≈ heart > lungs. A correlation analysis among human and rodent tissues identified rat liver as a suitable surrogate for predicting funbound for PFAS in human tissues (R2 ≥ 0.98). The funbound data resulting from this work and the rat liver prediction method offer input parameters and tools for toxicokinetic models for legacy and emerging PFAS.

Establishment of a semi-continuous scale-down clone screening model for intensified perfusion culture.

PURPOSE: Perfusion cultures have been extensively used in the biotechnology industry to achieve high yields of recombinant products, especially those with stability issue. The WuXiUP™ platform represents a novel intensified perfusion that can achieve ultra-high productivity. This study describes a representative scale-down 24-deep well plate (24-DWP) cell culture model for intensified perfusion clone screening. METHODS: Clonal cell lines were expanded and evaluated in 24-DWP semi-continuous culture. Cell were sampled and counted daily with the aid of an automated liquid handler and high-throughput cell counter. To mimic perfusion culture, 24-DWP plates were spun down and resuspended with fresh medium daily. Top clones were ranked based on growth profiles and productivities. The best performing clones were evaluated on bioreactors. RESULTS: The selected clones achieved volumetric productivity (Pv) up to 5 g/L/day when expressing a monoclonal antibody, with the accumulative harvest Pv exceeding 60 g/L in a 21-day cell culture. Product quality attributes of clones cultured in 24-DWP were comparable with those from bioreactors. A high seeding strategy further shortened the clone screening timeline. CONCLUSION: In this study, a 24-DWP semi-continuous scale-down model was successfully developed to screen for cell lines suitable for intensified perfusion culture.

Chelating Dual Interface for Efficient and Stable Crystal Growth and Iodine Defect Management in Sn-Pb Perovskite Solar Cells.

Suppressing Sn2+ oxidation and rationally controlling the crystallization process of tin-lead perovskite (Sn-Pb PVK) films by suitable bonding methods have emerged as key approaches to achieving efficient and stable Sn-Pb perovskite solar cells (PSCs). Herein, the chelating coordination is performed at the top and bottom interfaces of Sn-Pb PVK films. The chelation strength is stronger toward Sn2+ than Pb2+ by introducing oligomeric proanthocyanidins (OPC) at the bottom interface. This difference in chelation strength resulted in a spontaneous gradient distribution of Sn/Pb within the perovskite layer during crystallization, particularly enhancing the enrichment of Sn2+ at the bottom interface and facilitating the extraction and separation of photogenerated charge carriers in PSCs. Simultaneously, this top-down distribution of gradually increasing Sn content slowed down the crystallization rate of Sn-Pb PVK films, forming higher-quality films. On the top interface of the PVK, trifluoroacetamidine (TFA) was used to inhibit the generation of iodine vacancies (VI) through chelating with surface-uncoordinated Pb2+/Sn2+, further passivating defects while suppressing the oxidation of Sn2+. Ultimately, the PSCs with simultaneous chelation at both top and bottom interfaces achieved a power conversion efficiency (PCE) of 23.31% and an open-circuit voltage (VOC) exceeding 0.90 V. The stability of unencapsulated target devices in different environments also improved.

Study on Microstructure and Tribological Mechanism of Mo Incorporated (AlCrTiZr)N High-Entropy Ceramics Coatings Prepared by Magnetron Sputtering.

(AlCrTiZrMox)N coatings with varying Mo content were successfully prepared using a multi-target co-deposition magnetron sputtering system. The results reveal that the Mo content significantly affects the microstructure, hardness, fracture toughness, and tribological behavior of the coatings. As the Mo content in the coatings increases gradually, the preferred orientation changes from (200) to (111). The coatings consistently exhibit a distinct columnar structure. Additionally, the hardness of the coatings increases from 24.39 to 30.24 GPa, along with an increase in fracture toughness. The friction coefficient is reduced from 0.72 to 0.26, and the wear rate is reduced by 10 times. During the friction process, the inter-column regions of the coatings are initially damaged, causing the wear track to exhibit a wavy pattern. Greater frictional heat is generated at the crest of the wave, resulting in the formation of a MoO2 lubricating layer. The friction reaction helps to reduce the shear force during friction, demonstrating the lower friction coefficient of the (AlCrTiZrMox)N coatings. Both the hardness and fracture toughness work together to reduce the wear rate, and the (AlCrTiZrMox)N coatings show excellent wear resistance. Most notably, although the columnar structure plays a negative role in the hardness, it contributes greatly to the wear resistance.

Species-Specific Unbound Fraction Differences in Highly Bound PFAS: A Comparative Study across Human, Rat, and Mouse Plasma and Albumin.

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of fluorinated compounds which have yet to undergo comprehensive investigation regarding potential adverse health effects and bioaccumulative properties. With long half-lives and accumulative properties, PFAS have been linked to several toxic effects in both non-clinical species such as rat and mouse as well as human. Although biological impacts and specific protein binding of PFAS have been examined, there is no study focusing on the species-specific fraction unbound (fu) in plasma and related toxicokinetics. Herein, a presaturation equilibrium dialysis method was used to measure and validate the binding of 14 individual PFAS with carbon chains containing 4 to 12 perfluorinated carbon atoms and several functional head-groups to albumin and plasma of mouse (C57BL/6 and CD-1), rat, and human. Equivalence testing between each species-matrix combination showed positive correlation between rat and human when comparing fu in plasma and binding to albumin. Similar trends in binding were also observed for mouse plasma and albumin. Relatively high Spearman correlations for all combinations indicate high concordance of PFAS binding regardless of matrix. Physiochemical properties of PFAS such as molecular weight, chain length, and lipophilicity were found to have important roles in plasma protein binding of PFAS.

Characterization and Applications of Permeabilized Hepatocytes in Drug Discovery.

Hepatocytes are one of the most physiologically relevant in vitro liver systems for human translation of clearance and drug-drug interactions (DDI). However, the cell membranes of hepatocytes can limit the entry of certain compounds into the cells for metabolism and DDI. Passive permeability through hepatocytes can be different in vitro and in vivo, which complicates the human translation. Permeabilized hepatocytes offer a useful tool to probe mechanistic understanding of permeability-limited metabolism and DDI. Incubation with saponin of 0.01% at 0.5 million cells/mL and 0.05% at 5 million cells/mL for 5 min at 37°C completely permeabilized the plasma membrane of hepatocytes, while leaving the membranes of subcellular organelles intact. Permeabilized hepatocytes maintained similar enzymatic activity as intact unpermeabilized hepatocytes and can be stored at -80°C for at least 7 months. This approach reduces costs by preserving leftover hepatocytes. The relatively low levels of saponin in permeabilized hepatocytes had no significant impact on the enzymatic activity. As the cytosolic contents leak out from permeabilized hepatocytes, cofactors need to be added to enable metabolic reactions. Cytosolic enzymes will no longer be present if the media are removed after cells are permeabilized. Hence permeabilized hepatocytes with and without media removal may potentially enable reaction phenotyping of cytosolic enzymes. Although permeabilized hepatocytes work similarly as human liver microsomes and S9 fractions experimentally requiring addition of cofactors, they behave more like hepatocytes maintaining enzymatic activities for over 4 h. Permeabilized hepatocytes are a great addition to the drug metabolism toolbox to provide mechanistic insights.

Further accelerating biologics development from DNA to IND: the journey from COVID-19 to non-COVID-19 programs.

The Coronavirus Disease (COVID-19) pandemic has spurred adoption of revolutionary initiatives by regulatory agencies and pharmaceutical industry worldwide to deliver therapeutic COVID-19 antibodies to patients at unprecedented speed. Among these, timeline of chemistry, manufacturing and control (CMC), which involves process development and manufacturing activities critical for the assurance of product quality and consistency before first-in-human clinical trials, was greatly reduced from typically 12-15 months (using clonal materials) to approximately 3 months (using non-clonal materials) in multiple cases. In this perspective, we briefly review the acceleration approaches published for therapeutic COVID-19 antibodies and subsequently discuss the applicability of these approaches to achieve investigational new drug (IND) timelines of ≤10 months in over 60 COVID-19 and non-COVID-19 programs performed at WuXi Biologics. We are of the view that, with demonstrated product quality and consistency, innovative approaches used for COVID-19 can be widely applied in all disease areas for greater speed to clinic.

Comparison of Tumor Binding Across Tumor Types and Cell Lines to Support Free Drug Considerations for Oncology Drug Discovery.

Tumor binding is an important parameter to derive unbound tumor concentration to explore pharmacokinetics (PK) and pharmacodynamics (PD) relationships for oncology disease targets. Tumor binding was evaluated using eleven matrices, including various commonly used ex vivo human and mouse xenograft and syngeneic tumors, tumor cell lines and liver as a surrogate tissue. The results showed that tumor binding is highly correlated among the different tumors and tumor cell lines except for the mouse melanoma (B16F10) tumor type. Liver fraction unbound (fu) has a good correlation with B16F10 tumor binding. Liver also demonstrates a two-fold equivalency, on average, with binding of other tumor types when a scaling factor is applied. Predictive models were developed for tumor binding, with correlations established with LogD (acids), predicted muscle fu (neutrals) and measured plasma protein binding (bases) to estimate tumor fu when experimental data are not available. Many approaches can be applied to obtain and estimate tumor binding values. One strategy proposed is to use a surrogate tumor tissue, such as mouse xenograft ovarian cancer (OVCAR3) tumor, as a surrogate for tumor binding (except for B16F10) to provide an early assessment of unbound tumor concentrations for development of PK/PD relationships.

Gender and retention patterns among U.S. faculty.

Women remain underrepresented among faculty in nearly all academic fields. Using a census of 245,270 tenure-track and tenured professors at United States-based PhD-granting departments, we show that women leave academia overall at higher rates than men at every career age, in large part because of strongly gendered attrition at lower-prestige institutions, in non-STEM fields, and among tenured faculty. A large-scale survey of the same faculty indicates that the reasons faculty leave are gendered, even for institutions, fields, and career ages in which retention rates are not. Women are more likely than men to feel pushed from their jobs and less likely to feel pulled toward better opportunities, and women leave or consider leaving because of workplace climate more often than work-life balance. These results quantify the systemic nature of gendered faculty retention; contextualize its relationship with career age, institutional prestige, and field; and highlight the importance of understanding the gendered reasons for attrition rather than focusing on rates alone.

Rush hour-and-a-half: Traffic is spreading out post-lockdown.

Traffic congestion is ubiquitous in major cities around the world. Congestion is associated with a slew of negative effects, including delays and local air pollution. Because of the negative effects of congestion, governments invest billions of dollars into the highway system to try to reduce congestion and accommodate peak-hour automobile travel demand. The COVID-19 pandemic presented a significant disruption to transportation systems globally. One impact was a drastic reduction in travel, leading to free-flowing traffic conditions in many previously-congested cities. As lockdowns eased, traffic volumes returned to near-normal levels. However, the temporal pattern of demand may differ, due to increased remote work or other factors. In this article, we examine the temporal distribution of highway demand in California, using data from over 3,500 traffic sensors. We find that peak-hour automobile travel is spreading in the post-lockdown period. In addition to decreased traffic congestion, this finding also has implications for infrastructure investment. Roadways are generally sized based on peak-hour demand. As the peaks spread, some highway construction project may prove unnecessary. It may be possible to reallocate road space to other uses with fewer tradeoffs in terms of traffic congestion.

An illusion of predictability in scientific results: Even experts confuse inferential uncertainty and outcome variability.

Traditionally, scientists have placed more emphasis on communicating inferential uncertainty (i.e., the precision of statistical estimates) compared to outcome variability (i.e., the predictability of individual outcomes). Here, we show that this can lead to sizable misperceptions about the implications of scientific results. Specifically, we present three preregistered, randomized experiments where participants saw the same scientific findings visualized as showing only inferential uncertainty, only outcome variability, or both and answered questions about the size and importance of findings they were shown. Our results, composed of responses from medical professionals, professional data scientists, and tenure-track faculty, show that the prevalent form of visualizing only inferential uncertainty can lead to significant overestimates of treatment effects, even among highly trained experts. In contrast, we find that depicting both inferential uncertainty and outcome variability leads to more accurate perceptions of results while appearing to leave other subjective impressions of the results unchanged, on average.

A Ternary Composite with Medium Adsorption Confirms Good Reversibility of Li-Se Batteries.

For Li-Se batteries, cathode using carbonaceous hosts to accommodate Se performed modestly, whereas those applying metallic compounds with stronger chemical adsorption exhibited even more rapid capacity decay, the intrinsic reasons for which are still not clear. Herein, it is found that Se tends to precipitate on the surface of the electrode during cycling, and the precipitation speed depends on the polarization degree of the host. A further enhanced adsorption does not certainly generate better electrochemical activity, since hosts with overhigh adsorption ability are hard to desorb polyselenides, leading to catalyst passivation and rapid capacity decay. These findings encourage us to design a ternary anatase/rutile/titanium nitride (aTiO2 /rTiO2 /TiN@C) composite host, integrating good adsorption of TiO2 and rapid electron transport ability of TiN, and introducing rutile to weaken overall adsorption. The aTiO2 /rTiO2 /TiN@C composite with medium adsorption not only avoids rapid loss of active substances in electrolyte but also slows down the precipitation speed of Se. As a result, the aTiO2 /rTiO2 /TiN@C/Se electrode delivered good rate capability(154 mA h g-1 at 20 C) and good cycling stability(a low decay of 0.024% per cycle within 500 cycles at 2 C).

Formalizing tenure of Indigenous lands improved forest outcomes in the Atlantic Forest of Brazil.

Across the globe, the legal land rights and tenure of many Indigenous peoples are yet to be recognized. A growing body of research demonstrates that tenure of Indigenous lands improves livelihoods and protects forests in addition to inherently recognizing human rights. However, the effect of tenure on environmental outcomes has scarcely been tested in regions with high development pressure, such as those with persisting forest-agriculture conflicts. In this paper, we conduct an event study and a difference-in-differences analysis to estimate the average treatment effect of land tenure on forest cover change for 129 Indigenous lands in the Atlantic Forest of Brazil from 1985 to 2019. We found that forest outcomes in Indigenous lands improved following tenure compared to pretenure and that forest outcomes improved in tenured compared to nontenured lands. We also found that formalized tenure, rather than incomplete tenure, was necessary to improve forest outcomes. Our study is the first rigorous analysis of the effect of tenure on Indigenous lands in the globally important Atlantic Forest biome and contributes to a growing body of literature on the role of rights-based approaches to conservation. The evidence presented in this study may support efforts to secure the legal rights and autonomy of Indigenous peoples.

Rapidly accelerated development of neutralizing COVID-19 antibodies by reducing cell line and CMC development timelines.

Since the Coronavirus Disease 2019 (COVID-19) outbreak, unconventional cell line development (CLD) strategies have been taken to enable development of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-neutralizing antibodies at expedited speed. We previously reported a novel chemistry, manufacturing, and control (CMC) workflow and demonstrated a much-shortened timeline of 3-6 months from DNA to investigational new drug (IND) application. Hereafter, we have incorporated this CMC strategy for many SARS-CoV-2-neutralizing antibody programs at WuXi Biologics. In this paper, we summarize the accelerated development of a total of seven antibody programs, some of which have received emergency use authorization  approval in less than 2 years. Stable pools generated under good manufacturing practice (GMP) conditions consistently exhibited similar productivity and product quality at different scales and batches, enabling rapid initiation of phase I clinical trials. Clones with comparable product quality as parental pools were subsequently screened and selected for late-stage development and manufacturing. Moreover, a preliminary stability study plan was devised to greatly reduce the time required for final clone determination and next-generation sequencing-based viral testing was implemented to support rapid conditional release of the master cell bank for GMP production. The successful execution of these COVID-19 programs relies on our robust, fit for purpose, and continuously improving CLD platform. The speed achieved for pandemic-related biologics development may innovate typical biologics development timelines and become a new standard in the industry.

Labor advantages drive the greater productivity of faculty at elite universities.

Faculty at prestigious institutions dominate scientific discourse, producing a disproportionate share of all research publications. Environmental prestige can drive such epistemic disparity, but the mechanisms by which it causes increased faculty productivity remain unknown. Here, we combine employment, publication, and federal survey data for 78,802 tenure-track faculty at 262 PhD-granting institutions in the American university system to show through multiple lines of evidence that the greater availability of funded graduate and postdoctoral labor at more prestigious institutions drives the environmental effect of prestige on productivity. In particular, greater environmental prestige leads to larger faculty-led research groups, which drive higher faculty productivity, primarily in disciplines with group collaboration norms. In contrast, productivity does not increase substantially with prestige for faculty publications without group members or for group members themselves. The disproportionate scientific productivity of elite researchers can be largely explained by their substantial labor advantage rather than inherent differences in talent.

Optimizing prevalence estimates for a novel pathogen by reducing uncertainty in test characteristics.

Emergence of a novel pathogen drives the urgent need for diagnostic tests that can aid in defining disease prevalence. The limitations associated with rapid development and deployment of these tests result in a dilemma: In efforts to optimize prevalence estimates, would tests be better used in the lab to reduce uncertainty in test characteristics or to increase sample size in field studies? Here, we provide a framework to address this question through a joint Bayesian model that simultaneously analyzes lab validation and field survey data, and we define the impact of test allocation on inferences of sensitivity, specificity, and prevalence. In many scenarios, prevalence estimates can be most improved by apportioning additional effort towards validation rather than to the field. The joint model provides superior estimation of prevalence, sensitivity, and specificity, compared with typical analyses that model lab and field data separately, and it can be used to inform sample allocation when testing is limited.

Multi-functional Strategy: Ammonium Citrate-Modified SnO2 ETL for Efficient and Stable Perovskite Solar Cells.

The tin oxide (SnO2) electron transport layer (ETL) plays a crucial role in perovskite solar cells (PSCs). However, the heterogeneous dispersion of commercial SnO2 colloidal precursors is far from optimized, resulting in dissatisfied device performance with SnO2 ETL. Herein, a multifunctional modification material, ammonium citrate (TAC), is used to modify the SnO2 ETL, bringing four benefits: (1) due to the electrostatic interaction between TAC molecules and SnO2 colloidal particles, more uniformly dispersed colloidal particles are obtained; (2) the TAC molecules distributed on the surface of SnO2 provide nucleation sites for the perovskite film growth, promoting the vertical growth of the perovskite crystal; (3) TAC-doped SnO2 shows higher electron conductivity and better film quality than pristine SnO2 while offering better energy-level alignment with the perovskite layer; and (4) TAC has functional groups of C═O and N-H containing lone pair electrons, which can passivate the defects on the surface of SnO2 and perovskite films through chemical bonding and inhibit the device hysteresis. In the end, the device based on TAC-doped ETL achieved an increased power conversion efficiency (PCE) of 21.58 from 19.75% of the reference without such treatment. Meanwhile, the PSCs using the TAC-doped SnO2 as the ETL maintained 88% of their initial PCE after being stored for about 1000 h under dark conditions and controlled RH of 10-25%.

Quantifying hierarchy and dynamics in US faculty hiring and retention.

Faculty hiring and retention determine the composition of the US academic workforce and directly shape educational outcomes1, careers2, the development and spread of ideas3 and research priorities4,5. However, hiring and retention are dynamic, reflecting societal and academic priorities, generational turnover and efforts to diversify the professoriate along gender6-8, racial9 and socioeconomic10 lines. A comprehensive study of the structure and dynamics of the US professoriate would elucidate the effects of these efforts and the processes that shape scholarship more broadly. Here we analyse the academic employment and doctoral education of tenure-track faculty at all PhD-granting US universities over the decade 2011-2020, quantifying stark inequalities in faculty production, prestige, retention and gender. Our analyses show universal inequalities in which a small minority of universities supply a large majority of faculty across fields, exacerbated by patterns of attrition and reflecting steep hierarchies of prestige. We identify markedly higher attrition rates among faculty trained outside the United States or employed by their doctoral university. Our results indicate that gains in women's representation over this decade result from demographic turnover and earlier changes made to hiring, and are unlikely to lead to long-term gender parity in most fields. These analyses quantify the dynamics of US faculty hiring and retention, and will support efforts to improve the organization, composition and scholarship of the US academic workforce.

Phase control of quasi-2D perovskite thin films by adding MAPbI3 in the precursor solution.

Quasi two-dimensional (Q-2D) perovskite cells have attracted much attention due to their excellent stability compared to their 3D counterparts. However, the Q-2D perovskite thin films prepared by the solution method have been confirmed to be a mixture of small-n phases and large-n phases instead of a pure phase, where the amount and distribution of these phases have a great significance on the performance of Q-2D perovskite solar cells. Here, commercialized 3D perovskite powder was simply added to an ACI perovskite precursor solution to get a uniform and closely connected heterostructure in which the large-n phases can work as pathways for charge transfer. The characterization results of the films and devices show that the appropriate amount of MAPbI3 in the precursor solution could distribute the 3D phases homogeneously within the final film to promote the photovoltaic performance of the devices. Consequently, the power conversion efficiency of the Q-2D ACI perovskite solar cell has been increased from 10.4% to 13.82% (with a 32.8% performance improvement).