Microns In Diameter Research Articles

Running on Fumes: An Analysis of Fine Particulate Matter's Impact on Finish Times in Nine Major US Marathons, 2003-2019.

Under controlled conditions and in some observational studies of runners, airborne fine particulate matter smaller than 2.5 microns in diameter (PM2.5) is associated with exercise performance decrements. To assess the association between event-day fine particulate matter air pollution (PM2.5) and marathon finish times. Using a spatiotemporal machine-learning model, we estimated event-day racecourse-averaged PM2.5 concentrations for nine major US marathons (2003-2019). We obtained 1,506,137 male and 1,058,674 female finish times from 140 event-years of public marathon data. We used linear and quantile mixed models to estimate the mean and percentile-specific year and heat index-adjusted effect of 1µg/m3 higher event-day racecourse-averaged PM2.5 on marathon finish times in sex-stratified samples. Analyzing all finish times, 1µg/m3 higher race-day PM2.5 was associated with 32-s slower average finish times among men (95% confidence limits (CL) 30, 33s) and 25-s slower average finish times among women (95% CL 23, 27s). Quantile-specific associations of event-day PM2.5 with finish times were larger for faster-than-median finishers. While PM2.5 was generally associated with slower finish times in single-event models, there was effect heterogeneity, and most 95% confidence intervals included the null. Greater race-day PM2.5 was associated with slower average marathon finish times, with more pronounced effects in faster-than-median runners. While more research is needed to characterize effect heterogeneity across the performance spectrum, these findings show the impact of PM2.5 on marathon performance and the importance of considering data from multiple competitions when estimating PM2.5 effects from event-level data.

Hexagonal ZnO microdisk grown by mist chemical vapor deposition on c-plane sapphire substrate and lasing actions

Abstract Hexagonal ZnO microdisks were grown by mist chemical vapor deposition (mist-CVD) for 6 h. The microdisks when viewed from the top were typically hexagonal with diameters of a few micrometers, and their typical three-dimensional shape was a hexagonal pyramid. Sharp peaks appeared in the room-temperature photoluminescence (PL) spectra observed from a single hexagonal ZnO microdisk under high optically pumped conditions, and they are assumed to correspond to lasing actions. We also examined the temperature dependence of these sharp peaks in the PL spectra.


A Survey Paper on Plastic Solar Cell Technology

The demand of energy is increasing day by day so non-conventional source of energy has to be used. Sun is the nonconventional source of energy. Conventional solar panels convert solar energy into electrical energy. A plastic solar cell is the type of photovoltaic that makes use of organic electronics dealing with conductive organic polymers or small molecules for light absorption and charge transport to produce electricity from sunlight by the photovoltaic effect. Polymers Provide the Advantage of Solution Processing at Room Temperature, which is Less Expensive and Enables One to Use Plastics. Therefore, If Silicon Is Replaced with Polymer Nanowires, The Solar Cell Would Be Much Lighter and Ultimately Less Costly. These Solar Cells are Thin, Several Microns in Diameter, and Scavenge All the Rays from the Sun's Radiation. Plastic Solar Cell Technology is Based on Conjugated Polymers and Molecules. Polymer Solar Cells have Generated Considerable Interest Since it Provides Environmentally Friendly, Flexible, Lightweight, Low Cost, Possibility of High-Efficiency Solar Cells in the Last Couple of Decades. Plastic Solar Cells are More Efficient and Viable in Usage. This dissertation focuses on the development and optimization of plastic solar cell technology, in particular this potential towards flexible, lightweight, and cost-effective alternative sources to traditional silicon-based solar cells. The focus of the present research work is to find optimum organic materials for higher efficiency and stability in plastic solar cells, varying from conjugated polymers to small organic molecules. Some of the main goals are improving the charge transport mechanisms and optimizing the architecture of devices through state-of-the-art techniques of fabrication, like roll-to-roll printing and layer-by-layer deposition. The other key aspect is that the project assesses the environmental aspects and lifecycle of plastic solar cells to ensure an environmentally friendly production process. Huge preliminary results were achieved at high power conversion efficiencies and durability has been greatly improved, targeting very wide spread application from portable electronics up to building-integrated photovoltaics. Therefore, the discovery of plastic solar cells might be a major step for applicable solutions in renewable energy and towards overcoming the world's increasing energy challenges.

In-situ thermite combustion of micro magnesium fuel and lunar regolith simulant nanoparticles

Significant heat generation will be required for humans and equipment to the lunar night. In this work, we investigate the use of a sustainable in-situ thermite material as a fuel to provide the thermal energy required to keep components in working conditions. Magnesium is used as a reactive metal fuel, with lunar regolith simulant ball milled to sub-micron sizes as a solid oxidizer producing exothermic reactions. Enhanced combustion is achieved by controlling particle size and composition of the thermite mixture. Simulant particles ranging from hundreds of nanometers to tens of microns in diameter are tested, as well as the magnesium fuel compositions of 20% to 40% by weight. Small pellets of 3 mm in diameter and 3 mm in height are ignited by laser in both air and vacuum to quantify the combustion properties in different environments. High speed video, infrared camera and pyrometry techniques are taken to quantify the sample combustion properties. These pellets demonstrate the burning rates between 2.3 and 5.9 mm/s and temperatures ranging from 1100 to 1480 °C in vacuum and in air conditions, respectively. The samples composed of 20% magnesium and 80% regolith simulant release around 400 J/g, and sustain elevated temperatures for 15 s after combustion, making them suitable for in-situ lunar heating. Novel 2D temperature mapping allows greater understanding of the simulant thermite combustion. Based on the results, we discuss the design considerations that would need to be made in the creation of an in-situ metal fuel heating lunar system.

Empowering Advanced Photovoltaic Pioneers: A Bilateral Italy-USA Project

The sun bathes our planet with far more energy than humankind will possibly ever need (> 8,000 times the current demand). Yet, sustainable energy provision is among the most pressing challenges faced today. In order to unlock the vast potential of clean solar energy, we need disruptive technologies capable of efficiently harvesting sunlight, while being deployable at unprecedented scales. Available commercial photovoltaics (PV) can hardly cope sustainably with the sheer scale of this challenge. Silicon solar panels are the major commercial PV, they are based on a very Earth-abundant element, but their fabrication is extremely energy intensive. Conversely, thin film solar panels based on CdTe and Cu(In,Ga)Se2 require far less energy to produce, but some of their constituent elements are quite rare on the Earth’s crust. Hence, in both cases, the short term economic and ecologic sustainabilities are dubious. Recently, an advanced PV concept, called microconcentrator PV [1], has been conceived, which is free from raw materials availability constraints and is based on sunlight absorbers requiring low energy to grow. To demonstrate microconcentrator PV at laboratory scale, research groups have been using optical projection lithography (OPL), generating arrays of Cu(In,Ga)Se2 circles with tens of micrometer diameter. However, OPL cannot be scaled credibly to terawatt deployment. Industrial uptake of microconcentrator PV is only possible with a technique that ensures both high semiconductor quality, and high throughput at capital expenditure comparable or lower than currently available PVs. Inspired by the research of the US partner Gary Friedman [2], the Italian PI D. Colombara has patented a disrupting microfabrication technique [3] that could be scaled economically to deploy terawatts of microconcentrator PV. Our intent in this project is to leverage our complementary know-how to empower young PV pioneers and establish a lasting cooperation in this new promising field. Acknowledgements This work was supported in part by the Italian Ministry of Foreign Affairs and International Cooperation, grant number US23GR17. REMAP has received funding from the European Commission PathFinder Open programme under grant agreement No. 101046909. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or European Innovation Council and SME Executive Agency (EISMEA). Neither the European Union nor the granting authority can be held responsible for them.

FEATURES OF ELEMENTAL ANALYSIS OF DOLOMITES OF THE LOWER PERMIAN DEPOSITS BY X-RAY FLUORESCENCE SPECTROSCOPY

In this work, using the methods of scanning electron microscopy (SEM), X-ray phase analysis (XRF), X-ray fluorescence spectrometry (XFS) and thermogravimetric analysis (TGA), the physicochemical properties of dolomite rocks selected from one well at different depths of occurrence were studied. The SEM method shows that, depending on the depth of occurrence, dolomite is characterized by both ordinary crystals of rhombohedral morphology, the size of which varies from 50 to 80 microns along the diagonal axis, and unusual shapes, in the form of hexagonal plates up to 1 microns thick and 1 to 10 microns in diameter. It has been found that dolomite plates in places form spherical aggregates ranging in size from 20 to 40 microns. According to the RF analysis data, it was found that in samples of dolomite rock (of ordinary and unusual shape), after calcination at 1000 °C for 5 hours, there is a twofold increase in the molar stoichiometric ratio of Mg and Ca, compared with the initial (non-calcined) state of dolomite. By the XRD method, it was found that during calcination of dolomite samples, a phase transformation (CaMg(CO3)2 → CaO + MgO + 2CO2) is observed, in which lime (CaO) and periclase (MgO) phases are formed. Precision SEM studies have shown that periclase nanocrystals, whose size varies from 100 nm to 300 nm, are evenly distributed on the surface of larger lime fragments. As a result of numerous measurements of the X-ray spectra of the RF, it was found that the overlap of lime fragments with numerous periclase nanocrystals is the cause of a significant overestimation of the magnesium content after calcination of dolomite samples. It is concluded that in order to correctly conduct elemental analysis and obtain adequate information about the weight fraction of rock-forming oxides in dolomite samples, they must first be dissolved in hydrochloric acid. The method of sample preparation proposed by the authors for the correct elemental analysis of dolomite rocks has been tested on numerous samples, which showed convincing convergence of the data obtained by XRF (decomposition into rock-forming oxides) and XRF analysis.

New ichnofossil discovery in Mallorcan caves: Linking ancient and moden bat-ectoparasites coporolites.

Bat ectoparasitic ichnofossils can be useful to elucidate microbial mediation in mineralization processes of organic material, supplying valuable information on ancient parasitology and palaeoecology, among other topics. Rod-shaped features found in Cova des Pas de Vallgornera (Mallorca, Spain) are described for the first time. They are related to an ancient bat colony inhabiting the cave in the Early Pleistocene. These micro-morphologies are cylindrical in shape with sizes of a few hundred microns in length and less than one hundred microns in diameter. They are composed by a mash of microscopic calcite particles of different sizes and shapes, lying on deposits that contain phosphates and clay minerals. Some of these rod-shaped morphologies are covered in microscopic crystals, whose mineralogy is composed mainly of calcite, associated with dolomite, quartz and clays, These deposits are interpreted as fecal droplets of bat ectoparasites (probably Nycteribiidae), that infested an ancient bat colony living in the cave before the collapse blocking of its natural entrances; from 2.4 Ma to present, the cave has remained sealed, preserving these deposits as a new ichnofossil related to invertebrate's coprolites. The observation of similar micro-structures in Cova de sa Guitarreta, another Mallorcan cave nowadays used for breeding by bats, allowed to study a present-day analogue; in this case, the rod-shaped structures are composed by organic detritus with lenticular concave forms (red blood cells?) and minute mineral particles. Therefore, these cylindrical features could be envisaged as excreta from bloodsucking bat flies, being represented by present-day deposits (Cova de sa Guitarreta) as well as fossil coprolites in the case of Cova des Pas de Vallgornera.

Novel structure and composition of the unusually large germline determinant of the wasp Nasonia vitripennis.

Specialized, maternally derived ribonucleoprotein (RNP) granules play an important role in specifying the primordial germ cells in many animal species. Typically, these germ granules are small (~100 nm to a few microns in diameter) and numerous; in contrast, a single, extremely large granule called the oosome plays the role of germline determinant in the wasp Nasonia vitripennis. The organizational basis underlying the form and function of this unusually large membraneless RNP granule remains an open question. Here we use a combination of super-resolution and transmission electron microscopy to investigate the composition and morphology of the oosome. We show that the oosome has properties of a viscous liquid or elastic solid. The most prominent feature of the oosome is a branching mesh-like network of high abundance mRNAs that pervades the entire structure. Homologs of the core polar granule proteins Vasa and Oskar do not appear to nucleate this network, but rather are distributed adjacently as separate puncta. Low abundance RNAs appear to cluster in puncta that similarly do not overlap with the protein puncta. Several membrane-bound organelles, including lipid droplets and rough ER-like vesicles, are incorporated within the oosome, whereas mitochondria are nearly entirely excluded. Our findings show that the remarkably large size of the oosome is reflected in a complex sub-granular organization and suggest that the oosome is a powerful model for probing interactions between membraneless and membrane-bound organelles, structural features that contribute to granule size, and the evolution of germ plasm in insects.

Assessing the impact of meteorological factors and air pollution on respiratory disease mortality rates: a random forest model analysis (2017-2021).

Air pollution poses a significant threat to the health of all living beings on our planet. It has been scientifically established as a crucial factor affecting mortality rates, respiratory illnesses, mental well-being, and overall health. This study aimed to investigate the impact of air pollution and meteorological factors on respiratory disease mortality rates in Mashhad in 2017-2021 using a Random Forest (RF) model. At first, the daily statistics of meteorological parameters (pressure, humidity, temperature, solar radiation) during 2017-2021 were collected. The information related to pollutants pollutants such as PM2.5 (which is defined as particulate matter with less than 2.5 micrometer diameter and potentially harmful to humans), PM10 (Particles with a diameter of 10 micrometers or less that can negatively impact both human health and environmental conditions.), sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) was collected. the mortality statistics from respiratory diseases were collected from the Health system registaration (Sina). Then we used the RF regression model in Excel and Python software to investigate the interaction between the mentioned variables. The escalating trend of air pollution in Mashhad has led to an expected increase in respiratory-related hospitalizations. This necessitates urgent air pollution control measures. Concurrently, the study of pollutants and climatic elements, as substantiated by global epidemiological studies, is crucial. In Mashhad, the second most polluted city in Iran, climatic factors like humidity, sunshine duration, temperature, pressure, and sunlight intensity exacerbate atmospheric pollution levels, impacting human health and ecosystems. The R2, RSME, and MAE of RF model are 0.73, 2.52, and 2 which indicate that the model has successfully identified the relationship between input variables and the target variable, and it will exhibit high accuracy in predictions. In this study, the most influential factor was identified when the Variance Inflation (VI) factor reached a value of 0.548. This indicates a strong correlation between this factor and the death rate of patients during the specified period. Furthermore, we analyzed by excluding the day and month plans from our model. The results showed that the factor with the highest coefficient in the executive model was related to pressure, with a VI value of 0.049. This suggests that pressure plays a significant role in our model and has a substantial effect on the death rate of patients. In the study of various pollutants, it was found that PM10 had the most significant impact on the mortality rate of patients with respiratory conditions, with a VI of 0.039. Following PM10, the pollutants with the next highest coefficients of importance were NO2 (VI = 0.034), SO2 (VI = 0.033), PM2.5 (VI = 0.029), and CO (VI = 0.025), respectively. Furthermore, the study observed a notable increase in the mortality rate of respiratory patients over time. Specifically, for every five days, the death rate increased by 35.5%. Indeed, climate change and air pollution significantly contribute to the mortality rate from respiratory diseases. Therefore, it is crucial for individuals, particularly those with respiratory conditions, to heed meteorological warnings.

Long-term investigation of uniaxial compressive and self-sensing performances of ultra-high performance seawater sea-sand concrete incorporating superfine stainless wires: Insights into underlying mechanisms and theoretical models

Developing intrinsic self-sensing concrete is expected to provide a digital intelligence solution to address the infrastructure’s challenges in terms of safety, lifespan, resilience, and carbon emission reduction. Using seawater and sea-sand as well as corrosion-resistant conductive fillers to fabricate self-sensing ultra-high seawater sea-sand performance concrete (UHPSSC) with outstanding mechanical and durability performances is the prerequisite for realizing localized resource utilization and in-situ monitoring of marine infrastructure. However, the potential effect of ions from seawater and sea-sand on the long-term stability of mechanical and electrical performances cannot be ignored. This paper presents a long-term investigation of uniaxial compressive, electrical, and self-sensing performances of superfine stainless wires (SWs) reinforced UHPSSC under natural curing. The results show that incorporating 1.5% SWs improves the compressive strength, elastic modulus, peak strain, and toughness of UHPSSC by 25.0%, 11.7%, 33.8%, and 119.2%, respectively. The established statistical damage constitutive models based on Weibull strength theory highlight the roles of SWs in delaying crack initiation. The dense microstructure of SWs-reinforced UHPSSC inhibits the growth of expansive hydration products formed by corrosive ions, thus guaranteeing its long-term strength development. Additionally, due to incorporating 1.5% SWs, the electrical resistivity of UHPSSC is reduced by seven orders of magnitude, with a strain sensitivity of 119.1 under monotonic compressive loading and a monitoring stress range of 0-148.4 MPa, indicating that SWs-reinforced UHPSSC can sense its stress and strain while providing early warning of crack initiation and propagation. Benefiting from the rust-free property, micron diameter, and high aspect ratio of SWs, the primary conductive path of composites comprises the overlapping networks formed by low-content SWs, which are not influenced by the ion conduction of conductive ions. Hence, SWs-reinforced UHPSSC exhibits stable electrical resistivity and sensitivity during long-term curing, suggesting its considerable potential for long-term in-situ monitoring of marine infrastructure.

Intracellular diffusion in the cytoplasm increases with cell size in fission yeast.

Diffusion in the cytoplasm can greatly impact cellular processes, yet regulation of macromolecular diffusion remains poorly understood. There is increasing evidence that cell size affects the density and macromolecular composition of the cytoplasm. Here, we studied whether cell size affects diffusion at the scale of macromolecules tens of microns in diameter. We analyzed the diffusive motions of intracellular genetically-encoded multimeric 40 nm nanoparticles (cytGEMs) in the cytoplasm of the fission yeast Schizosaccharomyces pombe . Using cell size mutants, we showed that cytGEMs diffusion coefficients decreased in smaller cells and increased in larger cells. This increase in diffusion in large cells may be due to a decrease in the DNA-to-Cytoplasm ratio, as diffusion was not affected in large multinucleate cytokinesis mutants. In investigating the underlying causes of altered cytGEMs diffusion, we found that the proteomes of large and small cells exhibited size-specific changes, including the sub-scaling of ribosomal proteins in large cells. Comparison with a similar dataset from human cells revealed that features of size-dependent proteome remodeling were conserved. These studies demonstrate that cell size is an important parameter in determining the biophysical properties and the composition of the cytoplasm.

Air Pollution and Rheumatoid Arthritis Risk and Progression: Implications for the Mucosal Origins Hypothesis and Climate Change for RA Pathogenesis.

The goal of this review paper is to summarize the main research and findings regarding air pollution and its association with the risk and progression of rheumatoid arthritis (RA). The most studied components of air pollution included particulate matter of ≤ 2.5 microns in diameter (PM2.5), PM10, carbon monoxide (CO), nitrogen dioxide (NO2), nitric oxide (NOx), sulfur dioxide (SO2), and ozone (O3). In addition, specific occupations and occupational inhalants have been investigated for RA risk. Several studies showed that increased exposure to air pollutants increased the risk of developing RA, particularly seropositive RA. There was evidence of gene-inhalant interactions for seropositive RA risk. Fewer studies have been conducted on RA disease activity and bone erosions. Some studies suggest that patients with RA-associated interstitial lung disease may have worse outcomes if exposed to air pollution. We summarized associations between air pollution and increased RA risk, including RA-associated interstitial lung disease. Relatively few studies investigated air pollution and RA disease activity or other outcomes. These results suggest an important role of air pollution for seropositive RA development and suggest that climate change could be a driver in increasing RA incidence as air pollution increases.

Impact of Wildfire Smoke on PM2.5, CO, NO2, and SO2 Levels

Air pollution can negatively impact public and individual health, as well as the environment. This paper investigates the impact of wildfires on levels of different air pollutants in order to determine whether focusing on reducing wildfires can be an efficient way to reduce specific pollutants. By plotting the number of acres burning in wildfires along with the overall concentration of particulate matter less than 2.5 microns in diameter (PM2.5), carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) during a period of time in California, this paper estimates the contribution of wildfire smoke to the level of each pollutant. The results show that PM2.5 levels were the most heavily impacted by wildfires out of the four pollutants studied, and therefore actions to reduce the size and quantity of wildfires can be helpful to reduce the damage done by PM2.5 pollution. However, CO, NO2, and SO2 levels, while they may be correlated with fire size, are likely more strongly influenced by other factors. To minimize the harmful effects of these three pollutants, it may be more effective to focus on investigating other sources of CO, NO2, and SO2, such as the burning of fossil fuels in industrial machinery and motor vehicles.

A finite element analysis method for random fiber-aggregate 3D mesoscale concrete based on the crack bridging law

Mesoscale modeling is an emerging analytical method that can be used to study fiber-reinforced concrete. However, fine fibers with micrometer diameters are distributed in millions in a standard specimen, so it is impossible to establish a mesoscale model and further analyze it, which severely limits the investigation of the reinforcement mechanism of fine fibers on concrete. This paper efficiently established a highly applicable mesoscale analytical model for random fiber-polyhedral aggregate concrete in Abaqus software based on a comprehensive examination of the crack bridging law and the supplementation of the fiber spacing theory, combined with the improvement of the algorithms of aggregate generation, fiber arrangement, and the judgment of the fiber-aggregate contact by the secondary development method of Python, as well as the matrix-dual arrangement method. Additionally, basalt fiber concrete and mortar specimens were prepared and tested, and the parameters of the model were calibrated to verify the model's authenticity. The result shows that the method proposed in this paper can accurately and efficiently perform mesoscale concrete analysis with fine fibers. In the peak load stage, the fiber has the strongest alleviation effect (Δ = 0.033) on the matrix damage, 10 times that of the crack initiation stage (Δ = 0.003). With the development of damage, fiber stress increases gradually from the crack initiation stage (0.68 σfu), and the growth rate (41.53 %) is the largest at the peak load stage (σfu), which reveals the complex dynamic bridging effect of fiber on the matrix. This investigation proposes a novel and broad applicability methodology for the finite element analysis of fiber-reinforced aggregate mesoscale concrete.

Pharmaceutical Applications and Advances with Zetasizer: An Essential Analytical Tool for Size and Zeta Potential Analysis

: Zetasizer is an advanced device that measures various properties of particles or molecules suspended in a liquid medium. It is extensively used for evaluating the size of nanoparticles, colloids, and biomolecular particles, and for determining particle charge. There are several analytical techniques by which the size, zeta potential, and molecular weight can be determined, like Dynamic Light Scattering (DLS) that measures the size of particles in dispersed systems, which can range from sub-nanometers to several micrometers in diameter. Electrophoretic Light Scattering (ELS) analyzes the mobility and charge of particles, also known as the zeta potential. Static Light Scattering (SLS) determines the molecular weight of particles in a solution. The Zetasizer is part of the Zetasizer Advance range of benchtop systems available for laboratory use. The Zetasizer Ultra model offers unique measurement capabilities, such as Multi-angle Dynamic Light Scattering (MADLS) and particle concentration. These features offer a deeper understanding of samples, making the Zetasizer a vital instrument in numerous scientific and industrial applications. In this review, we have discussed Zetasizer’s principles for the determination of particle size, zeta potential, and molecular weight, along with its qualification and applications in different formulations.

Microcapsule preparation process research and current status of oilfield application

AbstractTraditional tertiary oil recovery methods are fraught with challenges such as significant reagent adsorption, voluminous injection requirements, limited sweep efficiency, and inadequate intelligent targeting. These issues lead to suboptimal displacement of residual oil, resulting in the inability to mobilize substantial crude oil resources and thus yielding low recovery rates. Microcapsules—spherical particles with micron or nanometer scale diameters—have been extensively utilized across various sectors, including food storage, targeted drug encapsulation, and fragrance containment, owing to their distinct advantages in controlled release, isolation, and targeted delivery. These applications have successfully achieved industrialization and commercialization. In recent years, numerous researchers have explored the application of microcapsule preparation processes to diverse facets of oil extraction, with the aim of further enhancing oil recovery (EOR). This article elucidates the mechanism of action of microcapsules, their preparation methods (encompassing in situ polymerization, interfacial polymerization, spray drying, solvent evaporation, phase separation, and supercritical CO2‐assisted techniques), characterization and evaluation methodologies, among other aspects. It encapsulates the current status and principal challenges associated with the application of microcapsule preparation processes in oilfield development and probes the potential and pivotal research directions for their oilfield applications.

Hot probe technique for thin films Seebeck coefficient measurement

A new experimental method using a 50 μm diameter hand fabricated hot probe of Pt90/10Rh alloy is proposed as a tool to measure the Seebeck coefficient of thin films deposited onto electrically insulated substrates. A thermal model for heat transfer inside the probe and to the sample was developed to simulate the corresponding temperature distributions. Simulations showed that the ratio of the temperature rise in the contact point to the average temperature of the probe evolves basically independent on electrical current and film-substrate properties. Moreover, the values of contact radius and thermal contact resistance should not be necessary known, but only the pairs which are best fitting the probe thermal resistance in contact with the film-substrate. This brings a great simplification in respect with certain AFM based hot probe methods for which is necessary to determine these two parameters by calibration of the two substrates with known thermal conductivity. The values can be further used to evaluate the Seebeck coefficient of the sample with a macroscopic probe, within 1 % precision. By variance to the classical measuring methods, which resort to a heater-heat sink ensemble instrumented with thermocouples, heated metallic rods with built-in thermocouples or microfabricated structures, the proposed method is fast, reliable and of higher spatial resolution. The method was validated by measuring the Seebeck coefficient on CdS, Bi and Cr thin films reference samples, respectively.

Robust Multifunctional Ultrathin 2 Nanometer Organic Nanofibers.

Ultrathin organic nanofibers (UTONFs) represent an emerging class of nanomaterials as they carry a set of favorable attributes, including ultrahigh specific surface area, lightweight, and mechanical flexibility, over inorganic counterparts, for use in biomedicine and nanotechnology. However, precise synthesis of uniform UTONFs (diameter ≤ 2 nm) with tailored functionalities remained challenging. Herein, we report robust multifunctional UTONFs using hydrophobic interaction-driven self-assembly of amphiphilic alternating peptoids containing hydrophobic photoresponsive azobenzene and hydrophilic hydroxyl moieties periodically arranged along the peptoid backbone. Notably, the as-crafted UTONFs are approximately 2 nm in diameter and tens of micrometers in length (an aspect ratio, AR, of ∼10000), exemplifying the UTONFs with the smallest diameter yielded via self-assembly. Intriguingly, UTONFs were disassembled into short-segmented nanofibers and controllably reassembled into UTONFs, resembling "step-growth polymerization". Photoisomerization of azobenzene moieties leads to reversible transformation between UTONFs and spherical micelles. Such meticulously engineered UTONFs demonstrate potential for catalysis, bioimaging, and antibacterial therapeutics. Our study highlights the significance of the rational design of amphiphiles containing alternating hydrophobic and hydrophilic moieties in constructing otherwise unattainable extremely thin UTONFs with ultrahigh AR and stimuli-responsive functionalities for energy and bionanotechnology.

(311) THE INJECTION OF CONCEPTION: A BRIEF REVIEW ON THE HISTORY INTRACYTOPLASMIC SPERM INJECTION (ICSI)

Abstract Introduction Intracytoplasmic sperm injection (ICSI) is one of the greatest breakthroughs in male infertility in recent history. This technique allows couples battling with infertility to conceive with just one single spermatozoon and one oocyte. Objective We sought to review the early history of ICSI. Methods Literature review for historical literature pertaining to ICSI was performed using Pubmed and Google Scholar. Results The first documented experiments with regards to fertility date back to the 1890s. In his original manuscript, Heape successfully transferred fertilized ova from one hare to another, resulting in viable offspring. In 1932, Pincus et al published a landmark in-vitro fertilization (IVF) study which proved that fertilized ova were able to mature and survive manipulation in vitro after a short period of incubation (20 hours). Chang et al expanded on this work in 1959 by demonstrating a more robust incubation and reimplantation protocol in hares. The first human IVF baby, Louise Brown, was born in 1978. It was not until 1962 when the first ICSI experiments were described. Hiramoto described experiments were fertilization of sea urchin occurred by injecting a single spermatozoon into single ooplasm. This same concept was later achieved with mice (1966) and hamsters (1977). As with any new technique, there were humble beginnings. The first studies using mammalian models demonstrated that only around 30% of oocytes survived the injection due to significant damage and lysis. In an effort to increase fertilization rates, several different techniques were trialed. In 1988, Kiessling et al published a technique were the zona pellucida (ZP) barrier was completely removed by treated the unfertilized ova with mild trypsin solution (digestive enzyme). While this did increase fertilization rates, polyspermy was an issue. As a result, another technique was born which focused on injecting sperm beyond ZP and into the perivitelline space. This technique was coined with the term sub-zonal insemination (SUZI) by Cohen et al in 1988. There was a significant decrease in polyspermy, however fertilization rates remained low. Efforts were then focused on not on abandoning, but refining techniques with better microsurgical precision. Dr. Gianpiero D. Palermo, one of the main pioneers of ICSI, helped with this refinement by ensuring that the lab was equipped with necessary equipment such an incubator and an anti-vibration table. Additionally, he helped developed small micro-needles (5 microns in diameter) and smoother micromanipulators to allow for steady pressure when injecting spermatozoa into ova. The first offspring using ICSI were achieved in rabbits (1988) and then bovine species (1990). Then, in 1992, when Palermo’s team was attempting SUZI, one single spermatozoon accidently pierced the oolemma and ooplasm of single oocyte. The next day, two pronuclei were noted, which confirmed the inception of ICSI. Four couples reported successful conception via ICSI that same year. Conclusions ICSI were made possible by the lessons learned from the development of IVF. This technique has since been refined and has provided infertile couples with the opportunity of conception for over 30 years. Disclosure No.

Compression Testing of Individual Battery Electrode Particles

The friability of powder materials used to fabricate battery electrodes is an important parameter in determining battery lifetime. Particulate electrode materials are subject to significant stresses during cell fabrication. While in use, battery cyclic charging and discharging induces mechanical stresses in the electrode materials which can significantly impact long-term stability.Our presentation will describe a novel micro-compression instrument and technique for determining the compression strength of individual particles as small as 1 micron in diameter. Brief examples of the technique used to characterize and compare the hardness of battery anode materials will be discussed. Further in-depth references will also be provided.