Common-path off-axis incoherent Fourier holography with a maximum overlapping interference area.

In this Letter, we present a new method for recording spatially incoherent common-path off-axis Fourier holograms. This method records the three-dimensional (3D) information of an object into a Fourier hologram without the need of any mechanical scanning with incoherent illumination. The proposed setup consists of two gratings to form a common-path configuration, and two customized cells to create a rotational and radial shearing interferometer. While the first grating is placed on the first image plane, the second grating shifts axially from the second image plane to build off-axis geometry. A lens is used to combine two beams to generate the maximum overlapping area at the hologram plane. Proof-of-concept experiments confirm the ability of such a system to achieve the maximum overlapping interference area, stability of the system against the vibration of surrounding environment, numerical reconstruction using only one fast Fourier transform, and 3D capability to capture a 3D object illuminated by an LED light.

Spatially incoherent common-path off-axis color digital holography.

We describe a new method for recording spatially incoherent common-path off-axis color digital holograms. We present the theoretical and experimental evidence to demonstrate an incoherent common-path off-axis color digital holographic (ICOCH) system capable of capturing information from three-dimensional color objects under incoherent illumination, both in transmission and reflection modes. Fresnel incoherent correlation holography (FINCH), a common-path system, is a frequently used incoherent holography technique. Our proposed system is conceptually similar to an advanced form of FINCH; moreover, it has three advantages over this advanced form of FINCH. First, removal of the spatial light modulator makes our system simpler and more cost-effective. Second, removal of the polarizer or analyzer allows for greater light throughput. Third, the off-axis optical configuration enables separation of zero-order and twin images with only a single exposure per color rather than requiring three exposures per color for in-line holography FINCH. Therefore, we believe that this simple and cost-effective system with high light throughput can acquire incoherent holograms for different colors involving single exposure for each color, which makes the ICOCH system suitable for many applications.

Spatially incoherent off-axis Fourier holography without using spatial light modulator (SLM).

We present a spatially incoherent dual path Fourier holographic system. Conceptually it is similar to Fourier incoherent single channel holography (FISCH). Although our incoherent off-axis Fourier holographic (IOFH) system does not have the robustness of a single channel system, it has three advantages over FISCH, with two being quite obvious from setup. First, no SLM is required, thus making the system simple and cost-effective. Second, it is capable of high light throughput because in FISCH, the use of SLM reduces light intensity in half by splitting one beam into two; furthermore, an analyzer is required to create interference which also reduces light intensity. The third advantage, which makes this IOFH system applicable even for on-axis samples (as opposed to samples in a half plane as is necessary for FISCH), is achieved by tilting one mirror. Here we demonstrate our system with a sample in half plane as in FISCH for different axial positions, and then by placing the object on an optical axis and tilting one mirror. The reconstructed images demonstrate holographic capabilities of our IOFH system for both on-axis and half plane sample locations.

Wireless Power Transfer for Autonomous Wearable Neurotransmitter Sensors.

In this paper, we report a power management system for autonomous and real-time monitoring of the neurotransmitter L-glutamate (L-Glu). A low-power, low-noise, and high-gain recording module was designed to acquire signal from an implantable flexible L-Glu sensor fabricated by micro-electro-mechanical system (MEMS)-based processes. The wearable recording module was wirelessly powered through inductive coupling transmitter antennas. Lateral and angular misalignments of the receiver antennas were resolved by using a multi-transmitter antenna configuration. The effective coverage, over which the recording module functioned properly, was improved with the use of in-phase transmitter antennas. Experimental results showed that the recording system was capable of operating continuously at distances of 4 cm, 7 cm and 10 cm. The wireless power management system reduced the weight of the recording module, eliminated human intervention and enabled animal experimentation for extended durations.

Sol-gel deposition of iridium oxide for biomedical micro-devices.

Flexible iridium oxide (IrOx)-based micro-electrodes were fabricated on flexible polyimide substrates using a sol-gel deposition process for utilization as integrated pseudo-reference electrodes for bio-electrochemical sensing applications. The fabrication method yields reliable miniature on-probe IrOx electrodes with long lifetime, high stability and repeatability. Such sensors can be used for long-term measurements. Various dimensions of sol-gel iridium oxide electrodes including 1 mm × 1 mm, 500 µm × 500 µm, and 100 µm × 100 µm were fabricated. Sensor longevity and pH dependence were investigated by immersing the electrodes in hydrochloric acid, fetal bovine serum (FBS), and sodium hydroxide solutions for 30 days. Less pH dependent responses, compared to IrOx electrodes fabricated by electrochemical deposition processes, were measured at 58.8 ± 0.4 mV/pH, 53.8 ± 1.3 mV/pH and 48 ± 0.6 mV/pH, respectively. The on-probe IrOx pseudo-reference electrodes were utilized for dopamine sensing. The baseline responses of the sensors were higher than the one using an external Ag/AgCl reference electrode. Using IrOx reference electrodes integrated on the same probe with working electrodes eliminated the use of cytotoxic Ag/AgCl reference electrode without loss in sensitivity. This enables employing such sensors in long-term recording of concentrations of neurotransmitters in central nervous systems of animals and humans.

Antituberculosis cycloartane triterpenoids from Radermachera boniana.

Three new triterpenoids, bonianic acids A (1) and B (2) and 3-O-acetyluncaric acid (3), were isolated from the leaves and twigs of Radermachera boniana, together with six known compounds, ursolic acid (4), oleanolic acid (5), 3-epi-oleanolic acid (6), 3α-O-acetyl-α-boswellic acid (7), ergosterol peroxide (8), and ß-sitostenone (9). Ergosterol peroxide (8) and bonianic acids A (1) and B (2) exhibited significant activity against Mycobacterium tuberculosis H37Rv strain.

Theoretical study of the adsorption of C1-C4 primary alcohols in H-ZSM-5.

The adsorption of C1-C4 primary alcohols at the Al12-O24(H)-Si12 intersection site in H-ZSM-5 is investigated using periodic density functional theory (DFT) calculations and adding a damped interatomic potential to the DFT results to account for dispersive van der Waals interactions (DFT-D). A good agreement between predicted and experimentally available adsorption enthalpies for C1-C3 alcohols is obtained. The effect of the H-ZSM-5 framework is sampled for adsorption of the C1-C4 alcohols in the straight and the zigzag channel. A variety of possible geometries, including hydrogen-bonded (physisorbed) and protonated (chemisorbed) complexes, are located as stable minima indicating that the potential energy surface connecting them is broad and very shallow. Experimental infrared (IR) spectra of the C1-C4 alcohols are interpreted based on harmonic frequency calculations for the most stable physisorbed and chemisorbed complexes. The stability of the adsorbed alcohols is governed by an interplay between their intrinsic basicity, van der Waals dispersive interactions and steric constraints exerted by the zeolite framework. In essence, steric constraints destabilize local hydrogen bonding and/or Coulomb alcohol-Brønsted acid site interactions while dispersive van der Waals interactions enhance the stability of physisorbed and chemisorbed complexes. Due to the prevalence of van der Waals interactions over steric constraints, C1-C4 alcohols adsorb preferentially in the more compact zigzag channel than in the straight channel. Both the physisorption and chemisorption energies increase linearly with 13 to 15 kJ mol(-1) per carbon atom in the straight and the zigzag channel, respectively.