Correcting Artifacts in Ratiometric Biosensor Imaging; an Improved Approach for Dividing Noisy Signals

The accuracy of biosensor ratio imaging is limited by signal/noise. Signals can be weak when biosensor concentrations must be limited to avoid cell perturbation. This can be especially problematic in imaging of low volume regions, e.g., along the cell edge. The cell edge is an important imaging target in studies of cell motility. We show how the division of fluorescence intensities with low signal-to-noise at the cell edge creates specific artifacts due to background subtraction and division by small numbers, and that simply improving the accuracy of background subtraction cannot address these issues. We propose a new approach where, rather than simply subtracting background from the numerator and denominator, we subtract a noise correction factor (NCF) from the numerator only. This NCF can be derived from the analysis of noise distribution in the background near the cell edge or from ratio measurements in the cell regions where signal-to-noise is high. We test the performance of the method first by examining two noninteracting fluorophores distributed evenly in cells. This generated a uniform ratio that could provide a ground truth. We then analyzed actual protein activities reported by a single chain biosensor for the guanine exchange factor (GEF) Asef, and a dual chain biosensor for the GTPase Cdc42. The reduction of edge artifacts revealed persistent Asef activity in a narrow band (∼640 nm wide) immediately adjacent to the cell edge. For Cdc42, the NCF method revealed an artifact that would have been obscured by traditional background subtraction approaches.

Novel Materials for Myco-Decontamination of Cyanide-Containing Wastewaters through Microbial Biotechnology

This study examined the effectiveness of decontamination of industrial cyanide-containing water using mycelium-based lignocellulosic materials. These results suggest that fungi biomass and plant substrates can be used successfully in the treatment of wastewater contaminated by cyanide. Fungi were isolated from old wood samples taken from a tailing dam with high cyanide content (more than 20 years in semi-submerged condition). All isolated fungi belonged to the genus Fusarium. Fusarium oxysporum Schltdl. is most effective for biodegradation of cyanide-containing wastewaters (even at low temperatures). The most optimal lignocellulosic composition for production of mycelium-based biomaterial for biodegradation of cyanide wastewater consists of a uniform ratio of Siberian pine sawdust and wheat straw. The high efficiency of mycelium-based materials has been experimentally proven in vitro at 15-25 ° C. New fungal biomaterials are provide decrease in the concentration of cyanide ions to 79% (P <0.001). Large-scale cultivation of fungi biomass was carried out by the periodic liquid-phase cultivation. The submerged biomass from bioreactor was used as an inoculum for the production of mycelium-based materials for bioremediation of cyanide wastewater in situ (gold mine tailing).

Correcting artifacts in ratiometric biosensor imaging; an improved approach for dividing noisy signals

The accuracy of biosensor ratio imaging is limited by signal/noise. Signals can be weak when biosensor concentrations must be limited to avoid cell perturbation. This can be especially problematic in imaging of low volume regions, e.g., along the cell edge. The cell edge is an important imaging target in studies of cell motility. We show how the division of fluorescence intensities with low signal-to-noise at the cell edge creates specific artifacts due to background subtraction and division by small numbers, and that simply improving the accuracy of background subtraction cannot address these issues. We propose a new approach where, rather than simply subtracting background from the numerator and denominator, we subtract a noise correction factor (NCF) from the numerator only. This NCF can be derived from the analysis of noise distribution in the background near the cell edge or from ratio measurements in the cell regions where signal-to-noise is high. We test the performance of the method first by examining two noninteracting fluorophores distributed evenly in cells. This generated a uniform ratio that could provide a ground truth. We then analyzed actual protein activities reported by a single chain biosensor for the guanine exchange factor Asef, and a dual chain biosensor for the GTPase Cdc42. The reduction of edge artifacts revealed persistent Asef activity in a narrow band (∼640 nm wide) immediately adjacent to the cell edge. For Cdc42, the NCF method revealed an artefact that would have been obscured by traditional background subtraction approaches.

Projection-Based Continuous 3D Printing Process With the Grayscale Display Method

The printing resolution and scale of projection-based 3D printing are affected by the pixel size and projected light power. An effective and versatile method to print complex constructs with high resolution and large area is still required since light distribution in printing systems is generally non-uniform. Here, we propose a projection-based continuous 3D printing with the grayscale display method to serve as an effective and precise way to improve printing resolution and area. The light characterization results demonstrated that the power density presented a non-uniform distribution, and the power values are linear to the excitation power. After modifying the masks into grayscale according to the duty cycle of the digital micro-mirror device (DMD) display, projected light exhibited improved uniformity along with expected light power and uniform ratio. To validate this developed printing process, the grayscale continuous printing of mesh and hexahedron frame constructs enabled a remarkable increase in the printing area and alleviation of under/over curing. This work reveals significant progress in printing of constructs at larger area and higher resolution in projection-based continuous 3D printing under non-uniform light.

Spherical diffuse Yukawa sources in relativity

A system containing only two diffuse massless sources (bearing a uniform ratio) of two different short range scalar fields is studied, according to Einstein's gravitational theory. One field is attractive, the other is repulsive. The distribution is in static equilibrium with spherical symmetry. A class of solutions of the field equations is obtained, where the solutions are nonsingular and have simple physical interpretation. A Schwarzschild-type gravitation is found at infinity, with the mass parameter solely arising from the scalar fields; these rapidly disappear with a Yukawa-type behaviour. The stability of the system is briefly stated, and the applicability of the model to large or small physical systems is pointed out.

Effect of Four Crude-Protein Concentrate Mixes upon Milk Production in Puerto Rico

A study was undertaken to compare the effect of four levels of crudeprotein in concentrate mixes on the milk production of cows fed cut forage as green-chop in Puerto Bico. The double-reversal experimental design was used in the study. The four levels of crude-protein used were: 12-, 16-, 20-, and 24-percent. Each of 54 milking cows were used for three consecutive lactation periods. Each animal received a uniform ratio of 1 pound of concentrate mix to every 2.5 pounds of milk, and the proportion of concentrate fed to milk produced was adjusted every 10 days. Milk production expressed as 4-percent fat-corrected milk was the only criterion for evaluation. Napier (Merker) grass, the roughage mostly consumed, varied in nutritive value from good to fair to poor, due to seasonal and annual differences. All animals in this study consumed Merker grass ad libitum. Milk production, concentrate, and roughage consumption data were recorded. Animal weights were recorded at the beginning of each period and then monthly thereafter. No statistical differences were observed in milk production between the four concentrate levels. It can be concluded that all four treatments were equally good. If concentrate feeds with lower crude-protein content can be purchased at less cost, dairymen will reduce their production costs by feeding them.