James W. Lee

Microalgae: a green source of renewable H2

This article summarizes recent advances in the field of algal hydrogen production. Two fundamental approaches are being developed. One involves the temporal separation of the usually incompatible reactions of O(2) and H(2) production in green algae, and the second involves the use of classical genetics to increase the O(2) tolerance of the reversible hydrogenase enzyme. The economic and environmental impact of a renewable source of H(2) are also discussed.

Characterization of Biochars Produced from Cornstovers for Soil Amendment

Through cation exchange capacity assay, nitrogen adsorption-desorption surface area measurements, scanning electron microscopic imaging, infrared spectra and elemental analyses, we characterized biochar materials produced from cornstover under two different pyrolysis conditions, fast pyrolysis at 450 °C and gasification at 700 °C. Our experimental results showed that the cation exchange capacity (CEC) of the fast-pyrolytic char is about twice as high as that of the gasification char as well as that of a standard soil sample. The CEC values correlate well with the increase in the ratios of the oxygen atoms to the carbon atoms (O:C ratios) in the biochar materials. The higher O:C ratio was consistent with the presence of more hydroxyl, carboxylate, and carbonyl groups in the fast pyrolysis char. These results show how control of biomass pyrolysis conditions can improve biochar properties for soil amendment and carbon sequestration. Since the CEC of the fast-pyrolytic cornstover char can be about double that of a standard soil sample, this type of biochar products would be suitable for improvement of soil properties such as CEC, and at the same time, can serve as a carbon sequestration agent.

Treatment of diffuse intrinsic brainstem gliomas: failed approaches and future strategies.

Diffuse intrinsic pontine gliomas constitute ~ 60-75% of tumors found within the pediatric brainstem. These malignant lesions present with rapidly progressive symptoms such as cranial nerve, long tract, or cerebellar dysfunctions. Magnetic resonance imaging is usually sufficient to establish the diagnosis and obviates the need for surgical biopsy in most cases. The prognosis of the disease is dismal, and the median survival is < 12 months. Resection is not a viable option. Standard therapy involves radiotherapy, which produces transient neurological improvement with a progression-free survival benefit, but provides no improvement in overall survival. Clinical trials have been conducted to assess the efficacy of chemotherapeutic and biological agents in the treatment of diffuse pontine gliomas. In this review, the authors discuss recent studies in which systemic therapy was administered prior to, concomitantly with, or after radiotherapy. For future perspective, the discussion includes a rationale for stereotactic biopsies as well as possible therapeutic options of local chemotherapy in these lesions.

Sustainability: the capacity of smokeless biomass pyrolysis for energy production, global carbon capture and sequestration

Smokeless biomass pyrolysis for biochar and biofuel production is a possible arsenal for global carbon capture and sequestration at gigatons of carbon (GtC) scales. The United States can annually harvest over 1.3 Gt (gigaton) of dry biomass. Use of the smokeless (clean and efficient) biomass-pyrolysis technology would enable the United States to converts its 1.3 Gt of annually harvestable biomass to biochar products equivalent to 325 million tons of stable carbon plus significant amount of biofuels including syngas and bio-oils. Currently, the world could annually harvest more than 6.5 GtC y−1 of biomass. The 6.5 GtC y−1 of biomass could be converted to biochar (3.25 GtC y−1) and biofuels (with heating value equivalent to that of 6500 million barrels of crude oil). Because biochar is mostly not digestible to microorganisms, a biochar-based soil amendment could serve as a permanent carbon-sequestration agent in soils/subsoil earth layers for thousands of years. By storing 3.25 GtC y−1 of biochar (equivalent to 11.9 Gt of CO2 per year) into soil and/or underground reservoirs alone, it would offset the worlds 8.67 GtC y−1 of fossil fuel CO2 emissions by about 38%. The worldwide maximum capacity for storing biochar carbon into agricultural soils (1411 million hectares) is estimated to be about 428 GtC. It may be also possible to provide a global carbon “thermostat” mechanism by creating biochar carbon energy storage reserves. This biomass-pyrolysis “carbon-negative” energy approach merits serious research and development worldwide to help provide clean energy and control global warming for a sustainable future of human civilization on Earth.

Nanoscale Photosynthesis: Photocatalytic Production of Hydrogen by Platinized Photosystem I Reaction Centers¶

Abstract A study of the photocatalytic production of molecular hydrogen from platinized photosystem I (PSI) reaction centers is reported. At pH 7 and room temperature metallic platinum was photoprecipitated at the reducing end of PSI according to the reaction, [PtCl6]2− + 4e− + hν → Pt↓ + 6Cl−, where it interacted with photogenerated PSI electrons and catalyzed the evolution of molecular hydrogen. The reaction mixture included purified spinach PSI reaction centers, sodium ascorbate and spinach plastocyanin. Experimental data on real-time catalytic platinum formation as measured by the onset and rates of hydrogen photoevolution as a function of time are presented. The key objective of the experiments was demonstration of functional nanoscale surface metalization at the reducing end of isolated PSI by substituting negatively charged [PtCl6]2− for negatively charged ferredoxin, the naturally occurring water-soluble electron carrier in photosynthesis. The data are interpreted in terms of electrostatic interactions between [PtCl6]2− and the positively charged surface of psaD, the ferredoxin docking site situated at the stromal interface of the photosynthetic membrane and which is presumably retained in our PSI preparation. A discussion of the rates of hydrogen evolution in terms of the structural components of the various PSI preparations as well as of those of the intact thylakoid membranes is presented.

A New Oxygen Sensitivity and Its Potential Application in Photosynthetic H2 Production

We have discovered a new competitive pathway for O2 sensitivity in algal H2 production that is distinct from the O2 sensitivity of hydrogenase per se. This O2 sensitivity is apparently linked to the photosynthetic H2 production pathway that is coupled to proton translocation across the thylakoid membrane. Addition of the proton uncoupler carbonyl cyanide-p-trifluoromethoxy- phenylhydrazone eliminates this mode of O2 inhibition on H2 photoevolution. This newly discovered inhibition is most likely owing to background O2 that apparently serves as a terminal electron acceptor in competition with the H2 production pathway for photosynthetically generated electrons from water splitting. This O2-sensitive H2 production electron transport pathway was inhibited by 3[3,4-dichlorophenyl]1,1-dimethylurea. Our experiments demonstrated that this new pathway is more sensitive to O2 than the traditionally known O2 sensitivity of hydrogenase. This discovery provides new insight into the mechanism of O2 inactivation of hydrogenase and may contribute to the development of a more-efficient and robust system for photosynthetic H2 production.

Integration of fossil energy systems with CO2 sequestration through NH4HCO3 production

The increasing anthropogenic CO2 emission and global warming (thus climate change) have challenged the United States and other countries to find new and better ways to meet the world’s increasing needs for energy while reducing greenhouse gases emissions. Here, we present a practical and revolutionary method that can sequester greenhouse gas emissions and, at the same time, benefit both agriculture and the economy. The proposed strategy utilizes an innovative application of chemical processes to convert CO2, NOx and SOx emissions into valuable fertilizers (mainly, NH4HCO3) that can enhance sequestration of CO2 into soil and subsoil earth layers, reduce NO3− contamination of groundwater and stimulate photosynthetic fixation of CO2 from the atmosphere. This invention integrates pollutant removing fertilizer production reactions with coal-fired power plants and other energy operations, resulting in a clean energy system that is in harmony with the earth ecosystem. This technology could contribute importantly to global CO2 sequestration and clean air protection. When this technology is in worldwide use, because of its high efficiency and carbon credit, in addition to the benefit of clean air protection and stimulation of photosynthetic fixation of CO2 from the atmosphere, maximally 300 million tons of CO2 per year (equivalent to about 5% of the CO2 emissions from coal-fired power plants in the world) from smokestacks can be placed into soil by the use of this technology.

Comparative analysis of pinewood, peanut shell, and bamboo biomass derived biochars produced via hydrothermal conversion and pyrolysis.

Biochars were produced from pinewood, peanut shell, and bamboo biomass through hydrothermal conversion (HTC) at 300 °C and comparatively by slow pyrolysis over a temperature range of 300, 400, and 500 °C. These biochars were characterized by FT-IR, cation exchange capacity (CEC) assay, methylene blue adsorption, as well as proximate and elemental analysis. The experimental results demonstrated higher retained oxygen content in biochars produced at lower pyrolysis temperatures and through HTC, which also correlated to the higher CEC of respective biochars. Furthermore, all types of biochar studied herein were capable of adsorption of methylene blue from solution and the adsorption did not appear to strongly correlate with CEC, indicating that the methylene blue adsorption appears to be dependent more upon the non-electrostatic molecular interactions such as the likely dispersive π-π interactions between the graphene-like sheets of the biochar with the aromatic ring structure of the dye, than the electrostatic CEC. A direct comparison of hydrothermal and pyrolysis converted biochars reveals that biochars produced through HTC have much higher CEC than the biochars produced by slow pyrolysis. Analysis by FT-IR reveals a higher retention of oxygen functional groups in HTC biochars; additionally, there is an apparent trend of increasing aromaticity of the pyrolysis biochars when produced at higher temperatures. The CEC value of the HTC biochar appears correlated with its oxygen functional group content as indicated by the FT-IR measurements and its O:C ratio.

Molecular Characterization of Inhibiting Biochar Water-Extractable Substances Using Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Biochar has gained significant interest worldwide for its potential use as both a carbon sequestration technique and soil amendment. Recently, research has shown that pinewood-derived biochar water extracts inhibited the growth of aquatic photosynthetic microorganisms, both prokaryotic and eukaryotic algae, while chicken litter- and peanut shell-derived biochar water extracts showed no growth inhibition. With the use of electrodialysis, the pinewood-derived biochar water extract is separated into 3 fractions (anode-isolated, center chamber retained, and cathode-isolated substances) all with varying toxic effects. Because of its ultrahigh resolution and mass precision, electrospray ionization (ESI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is utilized in this study to analyze biochar water extracts at a molecular level to enhance our understanding of the toxic nature of pinewood-derived biochar water extracts as compared to benign peanut shell-derived biochar water extracts. The molecular composition of pinewood-derived biochar water extracts shows unique carbohydrate ligneous components and sulfur containing condensed ligneous components that are both absent from the peanut shell water extracts and more prevalent in the anode-isolated substances. Using Kendrick mass defect analysis, we also determine that the most likely inhibitor species contain carboxyl and hydroxyl homologous series, both of which are characteristic functional groups hypothesized in our previous research for the inhibitor species. We have suggested that inhibition of aquatic photosynthetic microorganism growth is most likely due to degraded lignin-like species rich in oxygen containing functionalities. From the study conducted here, we show the potential of ultrahigh resolution FTICR-MS as a valuable analytical technique for determining whether certain biochars are safe and benign for use as carbon sequestration and soil amendment.

Oxygenic Photoautotrophic Growth Without Photosystem I

Contrary to the prediction of the Z-scheme model of photosynthesis, experiments demonstrated that mutants of Chlamydomonas containing photosystem II (PSII) but lacking photosystem I (PSI) can grow photoautotrophically with O2 evolution, using atmospheric CO2 as the sole carbon source. Autotrophic photosynthesis by PSI-deficient mutants was stable both under anaerobic conditions and in air (21 percent O2) at an actinic intensity of 200 microeinsteins per square meter per second. This PSII photosynthesis, which was sufficient to support cell development and mobility, may also occur in wild-type green algae and higher plants. The mutants can survive under 2000 microeinsteins per square meter per second with air, although they have less resistance to photoinhibition.