Manganese peroxidase (MnP) has been well studied for woody biomass degradation. MnP exhibits a biotechnological potential for producing lignin-based materials through Kraft lignin (KL) polymerization. MnP derived from Ceriporiopsis subvermispora (CsMnP) is particularly intriguing as this fungus predominantly utilizes MnP to degrade/modify lignin. Here, we investigated CsMnP's catalytic activity toward the phenolic β-O-4′ lignin substructure, utilizing guaiacylglycerol-β-guaiacyl ether (GGE) as the model substrate. The reaction carried out at 25 °C and pH 5 was monitored by RP-HPLC, leading to the isolation of five product peaks (P1 to P5) after 48 h. SEC analysis indicated that compounds in P1 to P5 had higher molecular weights than GGE, suggesting polymerization reactions. NMR analysis of P1 revealed that this compound contains two GGE segments, connected by a 5-5′ linkage. Furthermore, we demonstrated CsMnP's ability to modify KL at 25 °C and pH 5, yielding a product with a 360% higher molecular weight compared to untreated KL after 24 h. NMR spectra revealed the deprotonation of the benzenic ring in KL and polymerization through the possible formation of α-5′, 5-5′, and 4-O-5′ linkages. This study offers valuable insights into the enzymatic properties of CsMnP and presents a potential strategy for valorizing KL.
Conversion of microalgae biomass to bioethanol is actively being researched to establish a cost effective and sustainable production technology. The main challenge is to break down the carbohydrates content in the biomass to obtain fermentable sugar for subsequent fermentation process. This study focuses on the effectiveness of the usage phosphoric acid pretreatment and capability of Saccharomyces diastaticus as the fermentation microbe to produce ethanol. Scenedesmus dimorphus microalgae biomass was used as the feedstock due to its high carbohydrate content. Mild acid hydrolysis at various conditions were carried out on biomass and the hydrolysates were subjected to fermentation. The optimum condition of acid pre-treatment using phosphoric acid was determined in this study. Based on the results, bioethanol yield of 94% was obtained at optimum condition of 2.5% v/v phosphoric acid at temperature of 120 °C for 30 min. This study proved that combination of phosphoric acid pre-treatment process with Saccharomyces diastaticus yeast provides a practicable method for the production of bioethanol from microalgae.
Herein we present an inexpensive facile wet‐chemistry‐free approach to the transfer of chemical vapour‐deposited multiwalled carbon nanotubes to flexible transparent polymer substrates in a single‐step process. By controlling the nanotube length, we demonstrate accurate control over the electrical conductivity and optical transparency of the transferred thin films. Uniaxial strains of up to 140% induced only minor reductions in sample conductivity, opening up a number of applications in stretchable electronics. Nanotube alignment offers enhanced functionality for applications such as polarisation selective electrodes and flexible supercapacitor substrates. A capacitance of 17 F/g was determined for supercapacitors fabricated from the reported dry‐transferred MWCNTs with the corresponding cyclic voltagrams showing a clear dependence on nanotube length.
Rice straw (RS), an agricultural residue rich in carbohydrates, has substantial potential for bioethanol production. However, the presence of lignin impedes access to these carbohydrates, hindering efficient carbohydrate-to-bioethanol conversion. Here, we expressed versatile peroxidase (VP), a lignin-degrading enzyme, in Pichia pastoris and used it to delignify RS at 30 °C using a membrane bioreactor that continuously discarded the degraded lignin. Klason lignin analysis revealed that VP-treatment led to 35% delignification of RS. We then investigated the delignified RS by SEC, FTIR, and SEM. The results revealed the changes of RS caused by VP-mediated delignification. Additionally, we compared the saccharification and fermentation yields between RSs treated with and without VP, VP-RS, and Ctrl-RS, respectively. This examination unveiled an improvement in glucose and bioethanol production, VP-RS exhibiting up to 1.5-fold and 1.4-fold production, respectively. These findings underscore the potential of VP for delignifying RS and enhancing bioethanol production through an eco-friendly approach.
We report a gas ionizer based on arrays of microfabricated double-gated isolated vertically aligned carbon nanofibers (VA-CNFs) for application in low-power portable mass spectrometers. Field-emitted electrons from VA-CNFs are accelerated to high energy and subsequently collide with neutral gas molecules, leading to ionization/fragmentation of the molecules. Double-gated field-emitter arrays with isolated VA-CNF tips were fabricated using a photoresist planarization technique. Two types of devices were fabricated and characterized. The first type of device has the emitter tip in the same plane as the extraction gate, and the second type of device has the emitter tip 900 nm below the extraction gate. All devices were made using a process that results in gate and focus diameters of 1.7 and 4.2 μm, respectively. When operated as a field-emitted electron impact ionizer (EII), for the same ion current, the ionization efficiency (ratio of ions to emitted electrons) increased from 0.005 to 0.05 as the pressure is increased between 5×10 -6 and 1×10 -3 torr. In comparison with EIIs based on thermionic electron sources, the power dissipation reduced from >;1 W to 100 mW.
A study highlighting the benefits associated with the continuous separation of MnP- (or LiP-) depolymerized lignin fragments from the reaction medium using a membrane bioreactor.
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Polaritons in layered materials (LMs) are a promising platform to manipulate and control light at the nanometer scale. Thus, the observation of polaritons in wafer-scale LMs is critically important for the development of industrially relevant nanophotonics and optoelectronics applications. In this work, phonon polaritons (PhPs) in wafer-scale multilayer hexagonal boron nitride (hBN) grown by chemical vapor deposition are reported. By infrared nanoimaging, the PhPs are visualized, and PhP lifetimes of ≈0.6 ps are measured, comparable to that of micromechanically exfoliated multilayer hBN. Further, PhP nanoresonators are demonstrated. Their quality factors of ≈50 are about 0.7 times that of state-of-the-art devices based on exfoliated hBN. These results can enable PhP-based surface-enhanced infrared spectroscopy (e.g., for gas sensing) and infrared photodetector applications.
This paper presents the fabrication and characterization of carbon nanotubes cold cathodes and their improvement to photocathodes by adding p-i-n photodiodes in the device structure. Integration and operation of carbon nanotubes based photocathodes in prototype of dual x-ray tube is presented.
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