When condensed matter physics meets biology: Does superhydrophobicity benefiting the cryopreservation of human spermatozoa?

With the increasing demand in regenerative and reproductive medicine for successful conservation of living matter, the need of reliable platform in cell banking seems inevitable. Whilst the cells storage at cryogenic temperatures is a well-developed method, far less is known about the efficiency of nanotechnology in cryogenics. The primary objective of this study is to represent the first of its kind experimental results related to cryopreservation of human spermatozoa by means of superhydrophobic carbon soot coatings. The inclusion of soot-based water repellent interface during the freezing and thawing of human semen minimizes the solid-liquid interfacial area, retards the heat transfer rate and promotes the recovery of up to 80% of initial motility of post-thaw sperm cells. Our discoveries reveal a fundamentally new and exciting direction of development of cryopreservation technologies in the battle against painful biopsies and repetitive surgeries.     

Flame Experiments at the Advanced Light Source: New Insights into Soot Formation Processes

The following experimental protocols and the accompanying video are concerned with the flame experiments that are performed at the Chemical Dynamics Beamline of the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory^1-4. This video demonstrates how the complex chemical structures of laboratory-based model flames are analyzed using flame-sampling mass spectrometry with tunable synchrotron-generated vacuum-ultraviolet (VUV) radiation. This experimental approach combines isomer-resolving capabilities with high sensitivity and a large dynamic range^5,6. The first part of the video describes experiments involving burner-stabilized, reduced-pressure (20-80 mbar) laminar premixed flames. A small hydrocarbon fuel was used for the selected flame to demonstrate the general experimental approach. It is shown how species’ profiles are acquired as a function of distance from the burner surface and how the tunability of the VUV photon energy is used advantageously to identify many combustion intermediates based on their ionization energies. For example, this technique has been used to study gas-phase aspects of the soot-formation processes, and the video shows how the resonance-stabilized radicals, such as C₃H₃, C₃H₅, and i-C₄H₅, are identified as important intermediates⁷. The work has been focused on soot formation processes, and, from the chemical point of view, this process is very intriguing because chemical structures containing millions of carbon atoms are assembled from a fuel molecule possessing only a few carbon atoms in just milliseconds. The second part of the video highlights a new experiment, in which an opposed-flow diffusion flame and synchrotron-based aerosol mass spectrometry are used to study the chemical composition of the combustion-generated soot particles⁴. The experimental results indicate that the widely accepted H-abstraction-C₂H₂-addition (HACA) mechanism is not the sole molecular growth process responsible for the formation of the observed large polycyclic aromatic hydrocarbons (PAHs).     

Biased <Superscript>14</Superscript>C-derived organic carbon turnover estimates following black carbon input to soil: an exploration with RothC

The radiocarbon signature of the atmosphere is frequently used as a tracer to derive and validate turnover estimates of soil organic carbon (SOC). Such models often rely on steady-state assumptions and presume a direct correspondence between the atmospheric signature of CO₂ and that of residues entering the soil with or without a time-lag. The input of combustion products either from recent (i.e. charcoal) or fossil sources (e.g. diesel soot) violates this premise on account of its non-continuous delivery over time, the lack of ¹⁴C in fossil black carbon (BC) and its high inertness compared to plant residues. In this study, possible effects of BC inputs (0.6–5 t BC ha⁻¹ of different ¹⁴C age and supplied at different dates) on turnover calculations are discussed using hypothetical but realistic scenarios for two sites: cold grassland and temperate cropland. The carbon turnover model RothC 26.3 was used for the simulations. Turnover times may be over- or underestimated by up to 30%, depending on the underlying scenario. In the majority of cases, such effects are more pronounced and longer lasting at the colder site owing to its slower cycling. The models’ inherent inert carbon pool improves the match of turnover times compared to runs where inert carbon is not accounted for. This is, however, achieved at the expense of mismatching the amount of BC when the latter is ¹⁴C-young. The impact of BC on ¹⁴C-based turnover calculations is disproportionate with respect to its amount, and an independent record of carbon fluxes and/or BC inputs and characteristics is suggested whenever BC is assumed to play a role in the ecosystem under investigation.     

Biological effects of cigarette smoke, wood smoke, and the smoke from plastics: The use of electron spin resonance

This review compares and contrasts the chemistry of cigarette smoke, wood smoke, and the smoke from plastics and building materials that is inhaled by persons trapped in fires. Cigarette smoke produces cancer, emphysema, and other diseases after a delay of years. Acute exposure to smoke in a fire can produce a loss of lung function and death after a delay of days or weeks. Tobacco smoke and the smoke inhaled in a burning building have some similarities from a chemical viewpoint. For example, both contain high concentrations of CO and other combustion products. In addition, both contain high concentrations of free radicals, and our laboratory has studied these free radicals, largely by electron spin resonance (ESR) methods, for about 15 years. This article reviews what is known about the radicals present in these different types of smokes and soots and tars and summarizes the evidence that suggests these radicals could be involved in cigarette-induced pathology and smoke-inhalation deaths. The combustion of all organic materials produces radicals, but (with the exception of the smoke from perfluoropolymers) the radicals that are detected by ESR methods (and thus the radicals that would reach the lungs) are not those that arise in the combustion process. Rather they arise from chemical reactions that occur in the smoke itself. Thus, a knowledge of the chemistry of the smoke is necessary to understand the nature of the radicals formed. Even materials as similar as cigarettes and wood (cellulose) produce smoke that contains radicals with very different lifetimes and chemical characteristics, and mechanistic rationales for this are discussed. Cigarette tar contains a semiquinone radical that is infinitely stable and can be directly observed by ESR. Aqueous extracts of cigarette tar, which contain this radical, reduce oxygen to superoxide and thus produce both hydrogen peroxide and the hydroxyl radical. These solutions both oxidize alpha-1-proteinase inhibitor (a1PI) and nick DNA. Because of the potential role of radicals in smoke-inhalation injury, we suggest that antioxidant therapy (such as use of an inhaler for persons brought out of a burning building) might prove efficacious.     

Manipulated sperm motility via soot nanoparticles-induced biochemical alterations in human seminal plasma

Obtaining spermatozoa with progressive motility, via postejaculatory activation with pharmacological agents such as theophylline and pentoxifylline, is crucial for the success rate of assisted reproduction in couples with severe male factor infertility. Regrettably, the possibility of premature acrosome reactions and impared oocyte function questions the practical applicability of phosphodiesterase inhibitors. The rapid development of nanotechnologies promotes the use of hydrophobic rapeseed oil soot as a non-cytotoxic biomaterial for sperm motility activation, but the scarcity of knowledge regarding the interactions of soot with components from the seminal plasma hinders the eventual commercialization of this cutting-edge approach. Aiming to eliminate this shortcoming, the current study shows for the first time how the soot nanomaterials alter the biochemistry of human seminal plasma. Upon 270 min incubation with soot nanoparticles, the activity of AST, ALT, CK, LDH and GGT enzymes in the seminal plasma of ten patients changes inversely to the registered sperm motility (i.e., lower enzyme activity, higher sperm motility and vice versa). This phenomenon is primarily related to termination of the enzymes-substrate binding or extraction of enzymes from the gametes via chemical bonding with the soot. These novel mechanisms depend on the physicochemical features of used carbon nanomaterials, revealing opportunities for predictable tuning of the sperm reproductive potential.     

The weeds from the thatch roofs of medieval cottages from the south of England

Late medieval soot-coated thatch includes a number of very well preserved weeds as well as cereals or reeds. This paper investigates the weeds from the thatch roofs of 13 cottages from the south of England. It describes the exceptional preservation of the weeds which include plant parts rarely recorded in archaeological contexts and the information they can give about late medieval ecology and agronomy. One of the main implications of this study is the relation of this material to the usual archaeological samples and the possibility that remains of thatch may have been missed in past archaeobotanical investigations.