Engineered Nanogel Particles Enhance the Photoautotrophic Biosynthesis of Polyhydroxyalkanoate in Marine Photosynthetic Bacteria

Improving polyhydroxyalkanoate (PHA, a biodegradable plastic) production under photoautotrophic cultivation is challenging for sustainable bioproduction. In this study, we demonstrated the use of engineered nanogel particles to enhance PHA accumulation in the marine photosynthetic bacterium Rhodovulum sulfidophilum under photoautotrophic culture. We screened the effect of 13 engineered nanogel particles on the cell growth and PHA accumulation of R. sulfidophilum. The addition of anionic nanogel particles significantly enhanced PHA accumulation in R. sulfidophilum up to 157-fold compared to that without nanogel particles. By performing ¹³C tracer experiments and gas chromatography–mass spectrometry analysis, we confirmed that HCO₃⁻ was assimilated throughout the central carbon metabolism and that the accumulated PHA was indeed incorporated from HCO₃⁻. Our results indicate successful PHA production with the supplementation of engineered nanogel particles under photoautotrophic cultivation in R. sulfidophilum. Furthermore, the strategy of using engineered nanoparticles demonstrated in this study may be applicable to other microbial cell factories to produce other commodity metabolites

Progress and Plans for a US Laser System for the LISA Mission

NASA Goddard Space Flight Center is developing a master oscillator power amplifier (MOPA) laser transmitter for the ESA-led Laser Interferometer Space Antenna (LISA) mission. Taking advantage of our space laser experience and the emerging telecom laser technology, we are developing a full laser system for the LISA mission. Our research effort has included both master oscillator (MO) and power amplifier (PA) developments, and their environmental testing and reliability for space flight. Our current baseline for the MO is a low-mass, compact micro non-planar ring oscillator (m- NPRO) laser. The amplifier uses a robust mechanical design based on fiber components. We have performed laser system noise tests by amplitude- and frequency-stabilizing the PA output. We will describe our progress and plans to demonstrate a TRL 6 laser system, which is an essential step toward qualifying lasers for space applications, by 2021

Metal cations modulate the bacteriochlorophyll–protein interaction in the light-harvesting 1 core complex from Thermochromatium tepidum

AbstractThe light-harvesting 1 reaction center (LH1-RC) complex from Thermochromatium (Tch.) tepidum exhibits unusual Qy absorption by LH1 bacteriochlorophyll-a (BChl-a) molecules at 915nm, and the transition energy is finely modulated by the binding of metal cations to the LH1 polypeptides. Here, we demonstrate the metal-dependent interactions between BChl-a and the polypeptides within the intact LH1-RC complexes by near-infrared Raman spectroscopy. The wild-type LH1-RC (B915) exhibited Raman bands for the C3-acetyl and C13-keto CO stretching modes at 1637 and 1675cm−1, respectively. The corresponding bands appeared at 1643 and 1673cm−1 when Ca2+ was biosynthetically replaced with Sr2+ (B888) or at 1647 and 1669cm−1 in the mesophilic counterpart, Allochromatium vinosum. These results indicate the significant difference in the BChl–polypeptide interactions between B915 and B888 and between B915 and the mesophilic counterpart. The removal of the original metal cations from B915 and B888 resulted in marked band shifts of the C3-acetyl/C13-carbonyl νCO modes to ~1645/~1670cm−1, supporting a model in which the metal cations are involved in the fine-tuning of the hydrogen bonding between the BChl-a and LH1-polypeptides. Interestingly, the interaction modes were almost identical between the Ca2+-depleted B915 and Sr2+-depleted B888 and between B915 and Ca2+-substituted B888, despite the significant differences in their LH1 Qy peak positions and the denaturing temperatures, as revealed by differential scanning calorimetry. These results suggest that not only the BChl–polypeptide interactions but some structural origin may be involved in the unusual Qy red-shift and the enhanced thermal stability of the LH1-RC complexes from Tch. tepidum

A Multi-Wavelength IR Laser for Space Applications

We present a laser technology development with space flight heritage to generate laser wavelengths in the near- to mid-infrared (NIR to MIR) for space lidar applications. Integrating an optical parametric crystal to the LOLA (Lunar Orbiter Laser Altimeter) laser transmitter design affords selective laser wavelengths from NIR to MIR that are not easily obtainable from traditional diode pumped solid-state lasers. By replacing the output coupler of the LOLA laser with a properly designed parametric crystal, we successfully demonstrated a monolithic intra-cavity optical parametric oscillator (iOPO) laser based on all high technology readiness level (TRL) subsystems and components. Several desired wavelengths have been generated including 2.1 microns, 2.7 microns and 3.4 microns. This laser can also be used in trace-gas remote sensing, as many molecules possess their unique vibrational transitions in NIR to MIR wavelength region, as well as in time-of-flight mass spectrometer where desorption of samples using MIR laser wavelengths have been successfully demonstrated

Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. At NASA Goddard Space Flight Center (GSFC) we have been developing a laser-based technology needed to remotely measure CH4 from orbit. We report on our development effort for the methane lidar, especially on our laser transmitters and recent airborne demonstration. Our lidar transmitter is based on an optical parametric process to generate near infrared laser radiation at 1651 nanometers, coincident with a CH4 absorption. In an airborne flight campaign in the fall of 2015, we tested two kinds of laser transmitters --- an optical parametric amplifier (OPA) and an optical parametric oscillator (OPO). The output wavelength of the lasers was rapidly tuned over the CH4 absorption by tuning the seed laser to sample the CH4 absorption line at several wavelengths. This approach uses the same Integrated Path Differential Absorption (IPDA) technique we have used for our CO2 lidar for ASCENDS. The two laser transmitters were successfully operated in the NASAs DC-8 aircraft, measuring methane from 3 to 13 kilometers with high precision

Fiber-Based Laser MOPA Transmitter Packaging for Space Environment

NASAs Goddard Space Flight Center has been developing lidar to remotely measure CO2 and CH4 in the Earths atmosphere. The ultimate goal is to make space-based satellite measurements with global coverage. We are working on maturing the technology readiness of a fiber-based, 1.57-micron wavelength laser transmitter designed for use in atmospheric CO2 remote-sensing. To this end, we are building a ruggedized prototype to demonstrate the required power and performance and survive the required environment. We are building a fiber-based master oscillator power amplifier (MOPA) laser transmitter architecture. The laser is a wavelength-locked, single frequency, externally modulated DBR operating at 1.57-micron followed by erbium-doped fiber amplifiers. The last amplifier stage is a polarization-maintaining, very-large-mode-area fiber with ~1000 m2 effective area pumped by a Raman fiber laser. The optical output is single-frequency, one microsecond pulses with >450 J pulse energy, 7.5 KHz repetition rate, single spatial mode, and > 20 dB polarization extinction

Progress and Plans for a US Laser System for the LISA Mission

NASA Goddard Space Flight Center is developing a master oscillator power amplifier (MOPA) laser transmitter for the ESA-led Laser Interferometer Space Antenna (LISA) mission. Taking advantage of our space laser experience and the emerging telecom laser technology, we are developing a full laser system for the LISA mission. Our research effort has included both master oscillator (MO) and power amplifier (PA) developments, and their environmental testing and reliability for space flight. Our current baseline for the MO is a low-mass, compact micro NPRO (m-NPRO) laser. The amplifier uses a robust mechanical design based on fiber components. We have performed laser system noise tests by amplitude- and frequency-stabilizing the PA output. We will describe our progress and plans to demonstrate a TRL 6 laser system, which is an essential step toward qualifying lasers for space applications, by 2021

Fiber-Based Laser Transmitter Technology Maturation for Spectroscopic Measurements from Space

NASA's Goddard Space Flight Center has been developing lidar to remotely measure CO2 in the Earth's atmosphere. We have advanced the tunable laser technology to enable high-fidelity measurements from space. In this paper, we will report on the progress of fiber-based, 1.57-micron wavelength, laser transmitter that has demonstrated the optical performance required for a low earth orbiting instrument. The laser transmitter has been packaged and is undergoing environmental testing to demonstrate its technology readiness for space

Nature of Phase Transitions of Superconducting Wire Networks in a Magnetic Field

We study $I$-$V$ characteristics of periodic square Nb wire networks as a function of temperature in a transverse magnetic field, with a focus on three fillings 2/5, 1/2, and 0.618 that represent very different levels of incommensurability. For all three fillings, a scaling behavior of $I$-$V$ characteristics is found, suggesting a finite temperature continuous superconducting phase transition. The low-temperature $I$-$V$ characteristics are found to have an exponential form, indicative of the domain-wall excitations.Comment: 5 pages, also available at http://www.neci.nj.nec.com/homepages/tang.htm