Publications

The accurate spatial segregation into distinct phases within cell membranes coordinates vital biochemical processes and functionalities in living organisms. One of nature's strategies to localize reactivity is the formation of dynamic raft domains. Most raft models rely on liquid-ordered L-0 phases in a liquid-disordered L-d phase lacking correlation and remaining static, often necessitating external agents for phase separation. Here, we introduce a synthetic system of bicomponent glycodendrimersomes coassembled from Janus dendrimers and Janus glycodendrimers (JGDs), where lactose-lactose interactions exclusively drive lateral organization. This mechanism results in modulated phases across two length scales, yielding raft-like microdomains featuring nanoarrays at the nanoscale. By varying the density of lactose and molecular architecture of JGDs, the nanoarray type and size, shape, and spacing of the domains were controlled. Our findings offer insight into the potential primordial origins of rudimentary raft domains and highlight the crucial role of glycans within the glycocalyx.

JTD Keywords: Article, Artificial cells, Atomic force microscopy, Bicomponents, Bilayer, Bilayer membrane, Biochemical functionality, Biochemical process, Biological-membranes, Cell component, Cell membrane, Cellular parameters, Chemical interaction, Chemical structure, Chemistry, Cytology, Defined janus glycodendrimers, Dehydration, Dendrimer, Dendrimers, Dilution, Dimer, External agents, Fourier transform, Giant vesicles, Glycan, Glycans, Glycocalyx, Glycodendrimers, Janus dendrimer, Janus glycodendrimer, Lactose, Lateral organization, Lectin, Lipid rafts, Living organisms, Membrane damage, Membrane microdomain, Membrane microdomains, Membrane structure, Metabolism, Modulated phases, Molecule, Monomer, Nanoarrays, Oligosaccharide, Organization, Periodicity, Phase separation, Phase-separation, Phospholipids, Polysaccharide, Polysaccharides, Raft like domain, Relative humidity, Spatial segregation, Structure analysis, Sugars, Synthetic systems, Tetramer, Unclassified drug, Unilamellar vesicles, Water

JTD Keywords: alpha-tricalcium phosphate, cement, crystallinity, hydrolysis, hydroxyapatite, particle-size, powders, relative humidity, setting reaction, stability, tcp, vapor sorption, Calcium-phosphate, Moisture

High ambient temperature and humidity greatly increase the risk of hyperthermia and mortality, particularly in infants, who are especially prone to dehydration. World areas at high risk of heat stress include many of the low-and middle-income countries (LMICs) where most of their inhabitants have no access to air conditioning. This study aimed to design, evaluate, and test a novel low-cost and easy-to-assemble device aimed at preventing the risk of infant hyperthermia in LMICs. The device is based on optimizing negative heat transfer from a small amount of ice and transferring it directly to the infant by airflow of refrigerated air. As a proof of concept, a device was assembled mainly using recycled materials, and its performance was assessed under laboratory-controlled conditions in a climatic chamber mimicking realistic stress conditions of high temperature and humidity. The device, which can be assembled by any layperson using easily available materials, provided sufficient refrigerating capacity for several hours from just 1–2 kg of ice obtained from a domestic freezer. Thus, application of this novel device may serve to attenuate the adverse effects of heat stress in infants, particularly in the context of the evolving climatic change trends. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: air conditioning, ambient-temperature, death, heat, heat index, heat shock, heatwave, high ambient temperature, hyperthermia, low-cost refrigeration, low-middle income countries, mortality, negative heat transfer, Air conditioning, Algorithm, Article, Climate change, Cost benefit analysis, Environmental temperature, Heat index, Heat shock, Heat stress, Heat transfer, Heating, Heatwave, High ambient temperature, High temperature, Humidity, Hyperthermia, Low income country, Low-cost refrigeration, Low-middle income countries, Middle income country, Middle-income countries, Negative heat transfer, Prevention study, Refrigeration, Temperature stress, Thawing

The epidemic spread of many viral infections is mediated by the environmental conditions and influenced by the ambient humidity. Single virus particles have been mainly visualized by atomic force microscopy (AFM) in liquid conditions, where the effect of the relative humidity on virus topography and surface cannot be systematically assessed. In this work, we employed multi-frequency AFM, simultaneously with standard topography imaging, to study the nanoscale wetting of individual Tobacco Mosaic virions (TMV) from ambient relative humidity to water condensation (RH > 100%). We recorded amplitude and phase vs. distance curves (APD curves) on top of single virions at various RH and converted them into force vs. distance curves. The high sensitivity of multifrequency AFM to visualize condensed water and sub-micrometer droplets, filling gaps between individual TMV particles at RH > 100%, is demonstrated. Dynamic force spectroscopy allows detecting a thin water layer of thickness ⁓1 nm, adsorbed on the outer surface of single TMV particles at RH < 60%.

JTD Keywords: amplitude-modulation am-afm, atomic-force microscopy, capillary, force reconstruction, multifrequency afm, nanoscale wetting, persistence, reconstruction, relative-humidity, surfaces, tobacco mosaic virus (tmv), tobamovirus, transmission, water, Amplitude-modulation am-afm, Force reconstruction, Multifrequency afm, Nanoscale wetting, Tobacco mosaic virus (tmv), Tobacco mosaic virus (tmv), nanoscale wetting, Tobacco-mosaic-virus

The limit of detection (LOD) is a key figure of merit in chemical sensing. However, the estimation of this figure of merit is hindered by the non-linear calibration curve characteristic of semiconductor gas sensor technologies such as, metal oxide (MOX), gasFETs or thermoelectric sensors. Additionally, chemical sensors suffer from cross-sensitivities and temporal stability problems. The application of the International Union of Pure and Applied Chemistry (IUPAC) recommendations for univariate LOD estimation in non-linear semiconductor gas sensors is not straightforward due to the strong statistical requirements of the IUPAC methodology (linearity, homoscedasticity, normality). Here, we propose a methodological approach to LOD estimation through linearized calibration models. As an example, the methodology is applied to the detection of low concentrations of carbon monoxide using MOX gas sensors in a scenario where the main source of error is the presence of uncontrolled levels of humidity.

JTD Keywords: Semiconductor gas sensors, Metal-oxide sensors, Limit of detection, Non-linear, Humidity interference, Temperature modulation

A method for online decorrelation of chemical sensor signals from the effects of environmental humidity and temperature variations is proposed. The goal is to improve the accuracy of electronic nose measurements for continuous monitoring by processing data from simultaneous readings of environmental humidity and temperature. The electronic nose setup built for this study included eight metal-oxide sensors, temperature and humidity sensors with a wireless communication link to external computer. This wireless electronic nose was used to monitor the air for two years in the residence of one of the authors and it collected data continuously during 537 days with a sampling rate of 1 sample per second. To estimate the effects of variations in air humidity and temperature on the chemical sensors' signals, we used a standard energy band model for an n-type metal-oxide (MOX) gas sensor. The main assumption of the model is that variations in sensor conductivity can be expressed as a nonlinear function of changes in the semiconductor energy bands in the presence of external humidity and temperature variations. Fitting this model to the collected data, we confirmed that the most statistically significant factors are humidity changes and correlated changes of temperature and humidity. This simple model achieves excellent accuracy with a coefficient of determination R2 close to 1. To show how the humidity–temperature correction model works for gas discrimination, we constructed a model for online discrimination among banana, wine and baseline response. This shows that pattern recognition algorithms improve performance and reliability by including the filtered signal of the chemical sensors.

JTD Keywords: Electronic nose, Chemical sensors, Humidity, Temperature, Decorrelation, Wireless e-nose, MOX sensors, Energy band model, Home monitoring