Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userQuantum magnetic resonance microscopy
322
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Magnetic resonance spectroscopy is universally regarded as one of the most important tools in chemical and bio-medical research. However, sensitivity limitations typically restrict imaging resolution to length scales greater than 10 mu m. Here we bring quantum control to the detection of chemical systems to demonstrate high resolution electron spin imaging using the quantum properties of an array of nitrogen-vacancy (NV) centres in diamond. Our quantum magnetic resonance microscope selectively images electronic spin species by precisely tuning a magnetic field to bring the quantum probes into resonance with the external target spins. This provides diffraction limited spatial resolution of the target spin species over a field of view of ~50x50 mu m^2. We demonstrate imaging and spectroscopy on aqueous Cu2+ ions over microscopic volumes (0.025 mu m^3), with detection sensitivity at resonance of 104 spins/voxel, ~100 zeptomol (10^-19 mol). The ability to image, perform spectroscopy and dynamically monitor spin-dependent redox reactions and transition metal biochemistry at these scales opens up a new realm of nanoscopic electron spin resonance and zepto-chemistry in the physical and life sciences.
rate research
Read More
Multifocal microscopy (MFM) offers high-speed three-dimensional imaging through the simultaneous image capture from multiple focal planes. Conventional MFM systems use a fabricated grating in the emission path for a single emission wavelength band and one set of focal plane separations. While a Spatial Light Modulator (SLM) can add more flexibility, the relatively small number of pixels in the SLM chip, cross-talk between the pixels, and aberrations in the imaging system can produce non-uniform intensity in the different axially separated image planes. We present an in situ iterative SLM calibration algorithm that overcomes these optical- and hardware-related limitations to deliver near-uniform intensity across all focal planes. Using immobilized gold nanoparticles under darkfield illumination, we demonstrate superior intensity evenness compared to current methods. We also demonstrate applicability across emission wavelengths, axial plane separations, imaging modalities, SLM settings, and different SLM manufacturers. Therefore, our microscope design and algorithms provide an alternative to fabricated gratings in MFM, as they are relatively simple and could find broad applications in the wider research community.
We investigate the role of the noise in the mating behavior between individuals of Nezara viridula (L.), by analyzing the temporal and spectral features of the non-pulsed type female calling song emitted by single individuals. We have measured the threshold level for the signal detection, by performing experiments with the calling signal at different intensities and analyzing the insect response by directionality tests performed on a group of male individuals. By using a sub-threshold signal and an acoustic Gaussian noise source, we have investigated the insect response for different levels of noise, finding behavioral activation for suitable noise intensities. In particular, the percentage of insects which react to the sub-threshold signal, shows a non-monotonic behavior, characterized by the presence of a maximum, for increasing levels of the noise intensity. This constructive interplay between external noise and calling signal is the signature of the non-dynamical stochastic resonance phenomenon. Finally, we describe the behavioral activation statistics by a soft threshold model which shows stochastic resonance. We find that the maximum of the ensemble average of the input-output cross-correlation occurs at a value of the noise intensity very close to that for which the behavioral response has a maximum.
The batch fermentation process, inoculated by pulsed electric field (PEF) treated wine yeasts (S. cerevisiae Actiflore F33), was studied. PEF treatment was applied to the aqueous yeast suspensions (0.12 % wt.) at the electric field strengths of E=100 and 6000 V/cm using the same pulse protocol (number of pulses of n=1000, pulse duration of ti=100 mks, and pulse repetition time of dt=100 ms). Electro-stimulation was confirmed by the observed growth of electrical conductivity of suspensions. The fermentation was running at 30{deg}C for 150 hours in an incubator with synchronic agitation. The obtained results clearly evidence the positive impact of PEF treatment on the batch fermentation process. Electro-stimulation resulted in improvement of such process characteristics as mass losses, consumption of soluble matter content ({deg}Brix) and synthesis of proteins. It also resulted in a noticeable acceleration of consumption of sugars at the initial stage of fermentation in the lag phase. At the end of the lag phase (t=40 hours), consumption of fructose in samples with electrically activated inocula exceeded fructose consumption in samples with control inocula by 2.33 times when it was activated at E=100 V/cm and by 3.98 times after treatment at E=6000 V/cm. At the end of the log phase (120 hours of fermentation), 30% mass reduction was reached in samples with PEF-treated inocula (E=6000 V/cm), whereas the same mass reduction of the control sample required approximately, 20 hours of extra fermentation. The possible mechanisms of electro-stimulation are also discussed in details.
We present a method for achieving temporally and spatially precise photoactivation of neurons without the need for genetic expression of photosensitive proteins. Our method depends upon conduction of thermal energy via absorption by a dye or carbon particles and does not require the presence of voltage-gated channels to create transmembrane currents. We demonstrate photothermal initiation of action potentials in Hirudo verbana neurons and of transmembrane currents in Xenopus oocytes. Thermal energy is delivered by focused 50 ms, 650 nm laser pulses with total pulse energies between 250 and 3500 muJ. We document an optical delivery system for targeting specific neurons that can be expanded for multiple target sites. Our method achieves photoactivation reliably (70 - 90% of attempts) and can issue multiple pulses (6-9) with minimal changes to cellular properties as measured by intracellular recording. Direct photoactivation presents a significant step towards all-optical analysis of neural circuits in animals such as Hirudo verbana where genetic expression of photosensitive compounds is not feasible.
The liver performs critical physiological functions, including metabolizing and removing substances, such as toxins and drugs, from the bloodstream. Hepatotoxicity itself is intimately linked to abnormal hepatic transport and hepatotoxicity remains the primary reason drugs in development fail and approved drugs are withdrawn from the market. For this reason, we propose to analyze, across liver compartments, the transport kinetics of fluorescein-a fluorescent marker used as a proxy for drug molecules-using intravital microscopy data. To resolve the transport kinetics quantitatively from fluorescence data, we account for the effect that different liver compartments (with different chemical properties) have on fluoresceins emission rate. To do so, we develop ordinary differential equation transport models from the data where the kinetics are related to the observable fluorescence levels by measurement parameters that vary across different liver compartments. On account of the steep non-linearities in the kinetics and stochasticity inherent to the model, we infer kinetic and measurement parameters by generalizing the method of parameter cascades. For this application, the method of parameter cascades ensures fast and precise parameter estimates from noisy time traces.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
