Inanimate objects or surfaces contaminated with infectious agents, referred to as fomites, play an important role in the spread of viruses, including SARS-CoV-2, the virus responsible for the ...COVID-19 pandemic. The long persistence of viruses (hours to days) on surfaces calls for an urgent need for effective surface disinfection strategies to intercept virus transmission and the spread of diseases. Elucidating the physicochemical processes and surface science underlying the adsorption and transfer of virus between surfaces, as well as their inactivation, is important for understanding how diseases are transmitted and for developing effective intervention strategies. This review summarizes the current knowledge and underlying physicochemical processes of virus transmission, in particular via fomites, and common disinfection approaches. Gaps in knowledge and the areas in need of further research are also identified. The review focuses on SARS-CoV-2, but discussion of related viruses is included to provide a more comprehensive review given that much remains unknown about SARS-CoV-2. Our aim is that this review will provide a broad survey of the issues involved in fomite transmission and intervention to a wide range of readers to better enable them to take on the open research challenges.
Despite their rarity in peripheral blood, basophils play important roles in allergic disorders and other diseases including sepsis and COVID-19. Existing basophil isolation methods require many ...manual steps and suffer from significant variability in purity and recovery. We report an integrated basophil isolation device (i-BID) in microfluidics for negative immunomagnetic selection of basophils directly from 100 μL of whole blood within 10 minutes. We use a simulation-driven pipeline to design a magnetic separation module to apply an exponentially increasing magnetic force to capture magnetically tagged non-basophils flowing through a microtubing sandwiched between magnetic flux concentrators sweeping across a Halbach array. The exponential profile captures non-basophils effectively while preventing their excessive initial buildup causing clogging. The i-BID isolates basophils with a mean purity of 93.9% ± 3.6% and recovery of 95.6% ± 3.4% without causing basophil degradation or unintentional activation. Our i-BID has the potential to enable basophil-based point-of-care diagnostics such as rapid allergy assessment.
Aims
To test the relative importance of topography versus soil chemistry in defining tree species-habitat associations in a terra firme Amazonian forest.
Method
We evaluated habitat associations for ...612 woody species using alternative habitat maps generated from topography and soil chemistry in the 25-ha Amacayacu Forest Dynamics Plot, Colombian Amazon. We assessed the ability of each habitat map to explain the community-level patterns of species-habitat associations using two methods of habitat randomization and different sample size thresholds (i.e., species’ abundance).
Results
The greatest proportion of species-habitat associations arose from topographically-defined habitats (55% to 63%) compared to soil chemistry-defined (19% to 40%) or topography plus soil chemistry-defined habitats (18% to 42%). Results were robust to the method of habitat randomization and to sample size threshold.
Conclusions
Our results demonstrate that certain environmental factors may be more influential than others in defining forest-level patterns of community assembly and that comparison of the ability of different environmental variables to explain habitat associations is a crucial step in testing hypotheses about the mechanisms underlying assembly. Our results point to topography-driven hydrological variation as a key factor structuring tree species distributions in what are commonly considered homogeneous Amazonian terra firme forests.
Basophils are rare (~1% of peripheral blood leukocytes), yet potent effector cells that initiate and perpetuate a wide range of immunological responses. In particular, the role of basophils in food ...allergy is widely studied and has led to the emergence of a highly accurate ex vivo diagnostic test for food allergy: the basophil activation test (BAT). In contrast to commonly used food allergy diagnostic tests, i.e., skin prick test (SPT), allergen specific IgE (sIgE) measurement, and oral food challenge (OFC), the BAT provides highly sensitive and specific results (more than 90% across a range of allergens) while not subjecting individuals to potentially unsafe outcomes (e.g., anaphylaxis). Furthermore, basophil reactivity measured with BAT correlates well with severity and can be used to predict allergen thresholds that elicit a reaction in OFC. Despite the advantages of BAT over other methods, translating it to common clinical practice has been hampered. Motivated by the potential that BAT presents for changing the paradigm of food allergy diagnostics, my thesis dissertation focuses on various microfluidic approaches and aspects of measuring basophil activation that aim to increase clinical accessibility to BAT and to other future assays that probe basophil function. First, I investigated the utility of avidin as a basophil activation marker to evaluate whether avidin could enhance the predictive capability of BAT. Next, I developed various methods for rapid immunomagnetic isolation of basophils from whole blood to enable BAT-based diagnostic approaches and research that require purified basophils. Finally, I developed and characterized a novel device and analysis pipeline for increasing the clinical accessibility to BAT. Where applicable, I used computational methods to inform the design of the devices and analyzed data with machine learning.
The objective of this work is to understand multivariate elastic-mechanoluminescent (EML) light emission characteristics of copper-doped zinc sulfide (ZnS:Cu)-embedded polydimethylsiloxane (PDMS) ...self-sensing composites subjected to sinusoidal tensile loading and unloading cycles. To investigate the effect of tensile strain and strain rate on the EML light emission profiles (i.e., intensity and color) of the ZnS:Cu-PDMS composites, which are fabricated with different gage lengths (i.e., 150 and 4.7 mm). Each specimen is subjected to cyclic tensile loading and unloading with various maximum strains at various loading frequencies, and the EML light emission is video-recorded and subjected to image processing for quantifying intensity and color of EML light. The test specimen with 150-mm gage length is loaded and unloaded between 0% and a maximum tensile strain, which varies from 16% to 30%, at 1 Hz. The shorter specimen is subjected to tensile loading and unloading cycles between 0% and 15% strain at a frequency varying from 5 to 80 Hz. It is revealed that the EML light emission is triggered at a threshold tensile strain rate, and the light intensity increases as the composites undergo deformation during both loading and unloading cycles. This multistep EML light emission is attributed to the unique light emission mechanism of ZnS:Cu-embedded in soft PDMS matrix, which is a result of friction at the ZnS:Cu-PDMS interface, unlike other deformation-triggered light emitting EML materials.
Basophils are the rarest circulating white blood cells (WBCs), but they play important roles in allergic disorders and other diseases. To enhance diagnostic capabilities, it would be desirable to ...isolate and analyze basophils efficiently from small blood samples. In 100 μL of whole blood, there are typically ≈103 basophils, outnumbered by ≈105 WBCs and ≈108 red blood cells (RBCs). Basophils’ low abundance has therefore presented a significant challenge in their isolation from whole blood. Conventional in‐bulk basophil isolation methods require lengthy processing steps and cannot work with small volumes of blood. Herein, a parallelized integrated basophil isolation device (pi‐BID) is reported for the negative immunomagnetic selection of basophils directly from four samples of 100 μL of whole blood, in parallel, within 14 min including sample preparation time. The pi‐BID interfaces directly with standard sample tubes, and uses a single pressure source to drive the flow in parallel microfluidic channels. Compared with conventional in‐bulk basophil isolation, the pi‐BID is >3× faster, and has higher purity (≈93%) and similar recovery (≈67%). Compared with other microfluidic devices for the immunomagnetic isolation of WBC subtypes, the pi‐BID achieves 10× higher enrichment of target cells from whole blood, with no prior removal of RBCs necessary.
This study introduces a parallelized integrated basophil isolation device (pi‐BID) designed for the efficient isolation of basophils directly from whole blood. In <14 min, the pi‐BID processes four 100 μL whole blood samples in parallel. Compared with conventional in‐bulk basophil isolation, the pi‐BID is >3× faster, and has higher purity (≈93%) and similar recovery (≈67%).
Tropical forest responses to variation in water availability, which are critical for understanding and predicting the effects of climate change, depend on trait variation among trees.
We quantified ...interspecific and intraspecific variation in 18 branch, leaf and stomatal traits for 19–72 dominant tree species along a local topographic gradient in an aseasonal Amazon terra firme forest, and tested trait relationships with tree size, elevation, and species' topographic associations. We further tested whether correlation and coordination of traits vary among trees, among species and/or among trees within species.
Intraspecific trait variation was substantial and exceeded interspecific variation in 10 of 18 traits. For leaf acquisition traits, intraspecific variation was mainly related to tree topographic elevation, while most of the variation in branch, leaf and stomatal traits was related to tree size. Interspecific variation showed no clear relationships with species' habitat association. Although trait correlations and coordinations were generally maintained among trees and among species, bivariate relationships varied among trees within species, across habitat association classes and across tree size classes.
Our results demonstrate the magnitude and importance of intraspecific trait variation in tropical trees, especially as related to tree size. Furthermore, these results suggest that previous findings relating interspecific variation with topographic association in seasonal forests do not necessarily generalize to aseasonal forests.
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Read the free Plain Language Summary for this article on the Journal blog.
The relative importance of abiotic and biotic factors in shaping forest biomass stocks and fluxes remains a controversial issue. Here, using data gathered from 39 1 ha plots located in flooded and ...terra firme mature tropical lowland forests of the Amazon and Orinoquia regions of Colombia, we evaluated the importance of climate, soil fertility, and flooding, as well as tree taxonomic/phylogenetic diversity and forest structural properties, in determining the aboveground biomass stocks (AGB; Mg ha−1) and aboveground woody productivity (AWP; Mg ha−1 year−1). Using information‐theoretic multimodel inference and variance partitioning we found that forest structural features such as the number of trees with diameter at breast height ≥ 70 cm, and wood density, are the main drivers of variation in AGB. However, taxonomic diversity also contributes to AGB because it is associated with more large trees in these forests. In contrast, the key drivers of AWP in these forests were soil P and Mg concentrations, with no significant effects of diversity indices. These findings emphasize the need to include major soil cations other than N and P (e.g. Mg) in experimental studies to improve our understanding about the extent to which soil fertility can modulate increases in forest AWP due to climate change. Terra firme forests had higher AGB stocks than flooded forests, but both had similar AWP; and we found similar results for the drivers of AGB and AWP between flooded and terra firme forests. Our results provide limited evidence for strong effects of plant diversity on AGB or AWP. Therefore, we call for caution on generalizations of nature‐based initiatives aiming to preserve diversity based on maximizing carbon stocks and productivity, due to the complex nature of the processes controlling carbon accumulation and carbon fluxes in tropical forests.
Accurate estimates of forest biomass stocks and fluxes are needed to quantify global carbon budgets and assess the response of forests to climate change. However, most forest inventories consider ...tree mortality as the only aboveground biomass (AGB) loss without accounting for losses via damage to living trees: branchfall, trunk breakage, and wood decay. Here, we use ~151,000 annual records of tree survival and structural completeness to compare AGB loss via damage to living trees to total AGB loss (mortality + damage) in seven tropical forests widely distributed across environmental conditions. We find that 42% (3.62 Mg ha−1 year−1; 95% confidence interval CI 2.36–5.25) of total AGB loss (8.72 Mg ha−1 year−1; CI 5.57–12.86) is due to damage to living trees. Total AGB loss was highly variable among forests, but these differences were mainly caused by site variability in damage‐related AGB losses rather than by mortality‐related AGB losses. We show that conventional forest inventories overestimate stand‐level AGB stocks by 4% (1%–17% range across forests) because assume structurally complete trees, underestimate total AGB loss by 29% (6%–57% range across forests) due to overlooked damage‐related AGB losses, and overestimate AGB loss via mortality by 22% (7%–80% range across forests) because of the assumption that trees are undamaged before dying. Our results indicate that forest carbon fluxes are higher than previously thought. Damage on living trees is an underappreciated component of the forest carbon cycle that is likely to become even more important as the frequency and severity of forest disturbances increase.
Tree mortality is typically considered the only source of biomass loss in forest systems. A pervasive but commonly neglected biomass loss is the damage to living trees (i.e., branchfall, trunk breakage, wood decay). We show that 42% of total aboveground biomass loss is due to damage to living trees across seven tropical forests. Our results contrast with the typically low forest biomass losses estimated only from tree mortality and suggest that forest carbon turnover may be higher than previously thought. Since forest disturbance rates are expected to increase under climate change, biomass loss to damage is likely to become more important
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