Lensless imaging for simultaneous microfluidic sperm monitoring and sorting

5.3 million American couples of reproductive age (9%) are affected by infertility, among which male factors account for up to 50% of cases, which necessitates the identification of parameters defining sperm quality, including sperm count and motility. In vitro fertilization (IVF) with or without intra cytoplasmic sperm injection (ICSI) has become the most widely used assisted reproductive technology (ART) in modern clinical practice to overcome male infertility challenges. One of the obstacles of IVF and ICSI lies in identifying and isolating the most motile and presumably healthiest sperm from semen samples that have low sperm counts (oligozoospermia) and/or low sperm motility (oligospermaesthenia). Microfluidic systems have shown potential to sort sperm with flow systems. However, the small field of view (FOV) of conventional microscopes commonly used to image sperm motion presents challenges in tracking a large number of sperm cells simultaneously. To address this challenge, we have integrated a lensless charge-coupled device (CCD) with a microfluidic chip to enable wide FOV and automatic recording as the sperm move inside a microfluidic channel. The integrated system enables the sorting and tracking of a population of sperm that have been placed in a microfluidic channel. This channel can be monitored in both horizontal and vertical configuration similar to a swim-up column method used clinically. Sperm motilities can be quantified by tracing the shadow paths for individual sperm. Moreover, as the sperm are sorted by swimming from the inlet towards the outlet of a microfluidic channel, motile sperm that reach the outlet can be extracted from the channel at the end of the process. This technology can lead to methods to evaluate each sperm individually in terms of motility response in a wide field of view, which could prove especially useful, when working with oligozoospermic or oligospermaesthenic samples, in which the most motile sperm need to be isolated from a pool of small number of sperm.     

Experiments and modeling of ignition delay times, flame structure and intermediate species of EHN-doped stoichiometric n-heptane/air combustion

The combustion of stoichiometric Ethyl-hexyl-nitrate (EHN)-doped n-heptane/oxygen/argon and (EHN)-doped n-heptane/air mixtures, respectively, was investigated in a low-pressure burner with a molecular-beam mass spectrometer and ignition delay-time (τ_ign) measurements were performed in a high-pressure shock tube. The experiments with the low-pressure flame were used for the determination of the flame structure including concentration profiles of reactants, products and important intermediates in the flame. The shock tube experiments provided τ_ign for a temperature range of 690 K ? T ? 1275 K at a pressure of 40 ± 2 bar for stoichiometric and lean mixtures under engine relevant conditions. A chemical mechanism for n-heptane/EHN mixtures was developed from an automatically generated mechanism for n-heptane by manually adding reactions to describe the influence of EHN. This mechanism was validated against the shock-tube data for various temperatures, levels of EHN-doping and equivalence ratios by homogeneous reactor calculations.The ignition delay times predicted by the model agree well with the shock tube results for a large range of temperatures, equivalence ratios and EHN concentrations. The influence of EHN onto ignition delay was largest in the low-temperature regime (770-1000 K).Numerical analysis suggests that the prevalent reason for the ignition-enhancing effect of EHN is the formation of highly reactive heptyl radicals by thermal decomposition of EHN. Due to this comparatively simple and generic mechanism, EHN is expected to have a similar ignition-enhancing effect also for other hydrocarbon fuels.     

The role of external polyamines on photosynthetic responses, lipid peroxidation, protein and chlorophyll a content under the UV-A (352nm) stress in Physcia semipinnata

Physcia semipinnata was exposed to UV-A (352nm) and visible light (210, 800 and 2000mW/cm2) for 30min, 1, 2, 24, and 48h to seek the alterations in the PSII photosynthetic quantum yield, in response to radiation. Chlorophyll a fluorescence did not influence exposure to light, 210, 800 and 2000mW/cm2. Significant alterations of the photosynthetic quantum yield ratio occurred in response to increase in UV-A exposure time. The photosynthetic quantum yield ratio decreased in P. semipinnata following exposure to UV-A for 24 and 48h. The thalli of P. semipinnata treated with 1mM polyamine were not influenced during the exposure to UV-A for 24 and 48h. It was also found that exogenously spd added samples had higher chla content than spm and put added samples. In this study, we showed that lipid peroxidation levels between UV-A-treated samples and exogenously polyamine treated samples that were previously exposed to UV-A for 24 and 48h were significantly decreased. This result is the first record to indicate that external polyamines might have some protective role on photosystem II and membrane against UV-A stress.     

Eutectic isolation in Mg-Al-Cu-Li(-Y) alloys by centrifugal processing

Mg₅₆Al₃₀Li₇Cu₇ and Mg₅₀Al₃₀Y₆Li₇Cu₇ melts were processed for 2 h in a centrifuge at an inertial acceleration of 60 000g and a temperature of 530°C. Subsequent slow cooling across the melting temperature during continuous centrifugation leads to a pronounced stratification, with primary phases forming at the sample ends and binary and ternary eutectic microstructures forming in the middle of the sample, as resolved by scanning electron microscopy. In both cases, the ternary eutectic has the approximate nominal composition Mg₅₈Al₃₃Li₆Cu_2.5(Y_0.5). The implications of the use of high-temperature centrifugation as a new tool for finding deep eutectic compositions, which have the potential to form bulk metallic glasses, are discussed.     

Laser diagnostics of NO reburning in fuel-rich propene flames

Absolute NO concentrations were measured by laser-induced fluorescence (LIF) in three different fuel-rich non-sooting propene flames (φ=1.5, 1.8 and 2.3). The experiments were performed in low-pressure premixed propene flames with 0.2%-1% NO added. Laser diagnostics was applied as a tool for investigating reburn chemistry. The Q₂(25.5) line in the A-X(0,0) band was excited because of the small temperature dependence of its ground state population. The NO fluorescence lifetimes were measured directly and compared to theoretical values. The initial NO levels are strongly reduced in all three flames. According to modeling results, the HCN mole fraction increases strongly with stoichiometry. As guidelines for laser diagnostics applications in such systems, the modeling results were analyzed with respect to the main reaction channels and reaction partners in fuel-rich flames. Received: 1 March 2000 / Revised version: 20 April 2000 / Published online: 20 September 2000     

Responses of Pt/n-InP Schottky diode to electron irradiation in different temperature conditions

Different radiation and temperature effects on Schottky diodes are technologically important from radiation to sensing applications. We discussed irradiation and temperature dependent electronic properties of Pt/n-InP Schottky contact. Firstly we fabricated Pt/n-InP Schottky diode by magnetron sputtering technique. Then sample was exposed to 12 MeV electron irradiation. We measured I–V characteristics in 20, 160, 300 and 400 K before and after irradiation. Changes in forward currents for 160, 300 and 400 K were not remarkable but irradiation was effective only in 20 K slightly. Reverse currents of Pt/n-InP Schottky diode were increased in 20, 160, 300 and 400 K by irradiation.     

Controlled viable release of selectively captured label-free cells in microchannels

Selective capture of cells from bodily fluids in microchannels has broadly transformed medicine enabling circulating tumor cell isolation, rapid CD4(+) cell counting for HIV monitoring, and diagnosis of infectious diseases. Although cell capture methods have been demonstrated in microfluidic systems, the release of captured cells remains a significant challenge. Viable retrieval of captured label-free cells in microchannels will enable a new era in biological sciences by allowing cultivation and post-processing. The significant challenge in release comes from the fact that the cells adhere strongly to the microchannel surface, especially when immuno-based immobilization methods are used. Even though fluid shear and enzymes have been used to detach captured cells in microchannels, these methods are known to harm cells and affect cellular characteristics. This paper describes a new technology to release the selectively captured label-free cells in microchannels without the use of fluid shear or enzymes. We have successfully released the captured CD4(+) cells (3.6% of the mononuclear blood cells) from blood in microfluidic channels with high specificity (89% ± 8%), viability (94% ± 4%), and release efficiency (59% ± 4%). We have further validated our system by specifically capturing and controllably releasing the CD34(+) stem cells from whole blood, which were quantified to be 19 cells per million blood cells in the blood samples used in this study. Our results also indicated that both CD4(+) and CD34(+) cells released from the microchannels were healthy and amenable for in vitro culture. Manual flow based microfluidic method utilizes inexpensive, easy to fabricate microchannels allowing selective label-free cell capture and release in less than 10 minutes, which can also be used at the point-of-care. The presented technology can be used to isolate and purify a broad spectrum of cells from mixed populations offering widespread applications in applied biological sciences, such as tissue engineering, regenerative medicine, rare cell and stem cell isolation, proteomic/genomic research, and clonal/population analyses.     

Combined experiments to measure low sublimation pressures and diffusion coefficients of organometallic compounds

Vapor pressures and sublimation pressures of organometallic (metalorganic) compounds are needed in several processes like chemical vapor deposition (CVD). Thermobalances at ambient pressures are often used to study the evaporation of such compounds. At least three strategies are found in the literature to evaluate the results using different theoretical approaches. In some of the frequently used approaches the diffusion out of a crucible is neglected. We present a simple theoretical approach which describes the interrelation between the observed mass transfer rate and the physical variables of typical TGA set-ups. It turns out that the mass transfer rate at a given total pressure and temperature is mainly a function of the diffusion coefficient and the vapor pressure of the sublimating substance. The vapor pressures may be determined from an independent measurement using the Knudsen cell and combined with the TGA to obtain the diffusion coefficients. Experiments have been performed with two well studied substances naphthalene and phenanthrene to check the present strategy. Further measurements were then performed for the metal organic CVD relevant compounds: ferrocene and Tris(2,2,6,6-tetramethyl-3,5-heptanedianato)cobalt III [Co(tmhd)₃].     

Structural,magnetic and magnetocaloric properties of $$\hbox {Ni}_{54}\hbox {Mn}_{14}\hbox {Ga}_{27}\hbox {Fe}_{5}$$ Ni 54 Mn 14 Ga 27 Fe 5 : the impact of annealing time

Journal of Thermal Analysis and Calorimetry - The structural, magnetic and magnetocaloric properties of $$\hbox {Ni}_{54}\hbox {Mn}_{14}\, \hbox {Ga}_{27}\hbox {Fe}_{5}$$ Heusler alloy as a...     

Synthesis and characterization of graphene nanoplatelet-La0.7Ca0.3MnO3 composites

ABSTRACT

La_0.7Ca_0.3MnO₃ perovskite and its composites with graphene nanoplatelet (GNP) were prepared using a wet chemical method. The structural, magnetic and magnetocaloric properties of La_0.7Ca_0.3MnO₃: GNP composites were investigated to determine the effect of GNPs. The results of XRD analysis show that the synthesised powders can be almost indexed to pure phase orthorhombic La_0.7Ca_0.3MnO_3. The magnetic measurements demonstrate that 0.7 and 1% GNP amounts cause an increase in the Curie temperature (T_C), and for larger amounts of GNP, the T_C monotonically decreases, except for the sample with 10% GNP. The results obtained from the Arrott plots show that the magnetic phase transition of the samples transforms from the first to second order with increasing GNP amount. The changes in the magnetocaloric properties are interpreted in terms of perovskite phase formations via structural analysis. The amounts of graphene nanoplatelets in the oxide powders are correlated with the observed magnetocaloric properties. The best magnetocaloric performance with the maximum magnetic entropy change of 3.99 Jkg^?1K^?1 and refrigeration capacity of 90 Jkg^?1 was obtained at a 2?T magnetic field.