Clean energy: Hydrogen production from glycerol via dark fermentation

The demand for renewable and clean energy supplies is increasing because of depleting fossil fuels and global warming. Hydrogen (H2) is the only carbon-free energy source which is regarded as the cleanest fuel since water is the only product during combustion. Bio-hydrogen (bio-H2) production is promising because many organic wastes can be utilized as feedstocks. Bacteria fermentation, a similar process taking place during food digestion in our gut system, can be utilized to produce bio-H2. Glycerol, a waste byproduct from the manufacture of biodiesel, is a low-value chemical that can be converted intoH2. Biodiesel is a transportation fuel produced which is from algae. Converting glycerol intoH2 could be an economic advantage for many biodiesel industries. Adding fatty acids which are produced from oils such a safflower and sunflower oils can improve H2 production from glycerol during bacterial fermentation. Although bio-H2 production from glycerol through dark fermentation by using selected bacterium has been reported, the performance of H2 yield needs to be analyzed when mixed bacteria and H2-improving treatment are conducted. The main objective of this work was to establish a maximumH2 yield during the glycerol fermentation in the mixed cultures with the presence of fatty acids

Hydrogen Production During the Dark Fermentation of Glycero

The focus of this thesis was on the production of H2 from glycerol by mixed anaerobic cultures through dark fermentation. Laboratory scale experiments were conducted to demonstrate H2 production from glycerol. The impact of various factors was evaluated using different analytical and statistical methods. Three pH levels (5.5, 6.5, and 7.5) were examined to determine the effects of the initial pH on H2 production from glycerol. A hydrogen yield of 0.33 ± 0.03 mol H2 mol–1 glycerol was observed in cultures with the initial pH set at 5.5. Further experiments were focused on increasing the H2 yield using long chain fatty acids (LCFAs) as inhibitors together with glycerol in mixed anaerobic cultures with an initial pH of 5.5. Six LCFAs including lauric acid (LUA), myristic acid (MA), palmitic acid (PA), stearic acid (SA), oleic (OA), and linoleic acid (LA) were examined in this study. Higher H2 yields were observed in cultures fed PA, OA, or LA when compared to cultures fed with only glycerol. The H2 yield for the OA and LA treated cultures were 0.42 ± 0.01 and 0.46 ± 0.03 mol H2 mol–1 glycerol, respectively. In the LA and glycerol fed cultures, the H2 yield was 29% larger when compared to the glycerol control. Based on the electron balance, ethanol (EtOH) (approximately 23.1% of the total electron equivalents) and 1,3-propanediol (1,3 PDO) (approximately 50.0% of the total electron equivalents) were the major metabolites in the LA treated cultures, while approximately 6.5% and 7.9% electron equivalents were directed to H2 and acetate (Ac-) formation, respectively. A three-factor and three-level BBD model was conducted to maximize the H2 yield in cultures fed glycerol and LA. The initial pH levels (5.5, 6.5, 7.5), glycerol concentrations (1,300, 2,600, 5,110 mg L–1), and operational temperatures (22, 37, 52 °C) were three factors selected in this study. The highest H2 yield was 0.86 ± 0.02 mol H2 mol–1 glycerol at 55 °C, a pH of 5.5, and a glycerol concentration of 2,600 mg L–1. The predicted result was 0.84 mol H2 mol–1 glycerol at 55 °C, a pH of 5.5, and a glycerol concentration of 2,710 mg L–1 using the D-optimality analysis. Based on the designed BBD model, the optimum levels of three factors were significant when predicting the highest H2 yield by the D-optimality analysis

Localization of HIV-1 RNA in mammalian nuclei

The Rev protein of human immunodeficiency virus type 1 (HIV-1) facilitates the nuclear export of unspliced and partially spliced viral RNAs. In the absence of Rev, these intron-containing HIV-1 RNAs are retained in the nucleus. The basis for nuclear retention is unclear and is an important aspect of Rev regulation. Here we use in situ hybridization and digital imaging microscopy to examine the intranuclear distributions of intron-containing HIV RNAs and to determine their spatial relationships to intranuclear structures. HeLa cells were transfected with an HIV-1 expression vector, and viral transcripts were localized using oligonucleotide probes specific for the unspliced or spliced forms of a particular viral RNA. In the absence of Rev, the unspliced viral RNAs were predominantly nuclear and had two distinct distributions. First, a population of viral transcripts was distributed as approximately 10-20 intranuclear punctate signals. Actinomycin D chase experiments indicate that these signals represent nascent transcripts. A second, stable population of viral transcripts was dispersed throughout the nucleoplasm excluding nucleoli. Rev promoted the export of this stable population of viral RNAs to the cytoplasm in a time-dependent fashion. Significantly, the distributions of neither the nascent nor the stable populations of viral RNAs coincided with intranuclear speckles in which splicing factors are enriched. Using splice-junction-specific probes, splicing of human beta-globin pre-mRNA occurred cotranscriptionally, whereas splicing of HIV-1 pre-mRNA did not. Taken together, our results indicate that the nucleolus and intranuclear speckles are not involved in Rev regulation, and provide further evidence that efficient splicing signals are critical for cotranscriptional splicing

Simultaneous measurement of orbital angular momentum spectra in a turbulent atmosphere without probe beam compensation

In free-space optical (FSO) communications, the orbital angular momentum (OAM) multiplexing/demultiplexing of Bessel beams perturbed by atmospheric turbulence is of great significance. We used the Gerchberg-Saxton algorithm without a beacon beam to compensate for the aberrant helical phase of the Bessel beam distorted by the turbulent atmosphere. The optical vortex Dammann axicon grating was applied for the simultaneous measurement of the intensities of the demodulated spectra of the OAM modes of the Bessel beams disturbed by atmospheric turbulence. The experimental results demonstrate that the distorted phase of the Bessel beam can be compensated and the mode purity of the target OAM mode is enhanced from 0.85 to 0.92 in case of weak turbulence. Our results will improve the quality of the OAM modes of Bessel beam (de)multiplexing in FSO communication systems

Non-life insurance price dynamics: evidence from the Chinese insurance market

Non-life insurance prices may fluctuate due to economic and/or institutional factors; occasionally, the changes are cyclical. While the majority of previous studies relating to insurance price dynamics adopt data from developed economies, this paper uses data from China to provide new evidence. This study tests the long-term and short-term effects of real gross domestic product (GDP), interest rate and rate of stock market return on the prices of different lines of non-life insurance, i.e., property-liability insurance and personal accident insurance. The results indicate that the price dynamics of property-liability insurance are generally similar to those of developed countries, except for the effect of GDP, while price determination of personal accident insurance seems to be affected by a wider range of economic and institutional variables and has its own features. The price dynamics of non-life insurance in China have been identified as being connected to the country-specific economic and institutional environments

KS-Net: Multi-band joint speech restoration and enhancement network for 2024 ICASSP SSI Challenge

This paper presents the speech restoration and enhancement system created by the 1024K team for the ICASSP 2024 Speech Signal Improvement (SSI) Challenge. Our system consists of a generative adversarial network (GAN) in complex-domain for speech restoration and a fine-grained multi-band fusion module for speech enhancement. In the blind test set of SSI, the proposed system achieves an overall mean opinion score (MOS) of 3.49 based on ITU-T P.804 and a Word Accuracy Rate (WAcc) of 0.78 for the real-time track, as well as an overall P.804 MOS of 3.43 and a WAcc of 0.78 for the non-real-time track, ranking 1st in both tracks.Comment: Accepted to ICASSP 2024; Rank 1st in ICASSP 2024 Speech Signal Improvement (SSI) Challeng

Adaptability of root morphology and growth of two forage grass species in response to salt stress

The cultivated Echinochloa frumentacea (Roxb.) Link and Echinochloa crusgalli (L.) Beauv. var. mitis (Pursh) Peter are two valuable grass species that are widely used in improving saline-alkali soil. Here we conducted a pot experiment combined with roots morphological analysis to investigate the adaptability of grass roots to saline stress environments, with cultivated E. frumentacea and E. crusgalli being subjected to salt treatments of 0 (CK), 100, 220, and 340 mmoL·L−1. Results indicated that E. frumentacea had longer primary roots with fewer root hairs and lower local branching density than E. crusgalli, with the root volume of E. frumentacea being 1.43 times greater than that of E. crusgalli. The aboveground biomass of both grasses decreased significantly (p < 0.05) with increasing salt concentrations, whereas the root-to-shoot ratio exhibited the opposite trend, suggesting the preferential allocation of photosynthetic products to the roots under salt stress. The total length, surface area, and tip number of fine roots and the growth of coarse roots (d > 2.00 mm) showed significant differences (p < 0.05) between the two grass species. Different concentrations of salt stress had inconsistent effects on the biomass and radial growth of roots for grasses. The cultivated E. frumentacea seems to adopt an adapt strategy of gradually increasing its root thickness, root hairs, and root density under increasing salt stress. E. crusgalli, on the other hand, employed a strategy of increasing root length, maintaining uniform thickness, and developing root hairs

Middle-Late Jurassic magmatism in the west central Lhasa subterrane, Tibet: Petrology, zircon chronology, elemental and Sr-Nd-Pb-Hf-Mg isotopic geochemistry

Mesozoic magmatic rocks are widespread in the Lhasa terrane, but most of them are of cretaceous age. Because Jurassic rocks are relatively rare and our knowledge on such earlier magmatism in the context of the tectonic setting and evolution is limited. In this study, we focus on the mid-late Jurassic granitoids that occur in the west central Lhasa subterrane. We present the results of a systematic study of these granitoid rocks of tonalite composition together with the hosted mafic magmatic enclaves. We dated 4 representative tonalite samples and 2 enclaves using zircon U-Pb method that gives the age range of 167–154 Ma. All these samples have Sr-Nd-Pb isotopic compositions (87Sr/86Sr = 0.713941–0.718417, εNd(t) = −14 to −9.8, 206Pb/204Pb = 18.806–18.936, 207Pb/204Pb = 15.739–15.764, 208Pb/204Pb = 39.257–39.798) similar to the composition of gneisses from the basement of the Lhasa terrane, suggesting that magmas parental to these mid-late Jurassic granitoids of tonalitic composition are of largely crustal origin, which is also supported by the petrographic observations. Both of the tonalite samples and the mafic enclaves have a wide span of zircon εHf(t) of −15.9 to −0.2 and − 13.8 to −7.4, respectively. These samples also show varying δ26Mg ranging from −0.40 to −0.18, with an average δ26Mg = −0.27 ± 0.06‰ (2SD) that is best understood as representing the Mg composition of the continental crust of the Lhasa terrane. All these observations allow us to conclude that basaltic melts derived from metasomatized mantle were involved in the petrogenesis of these granitoids. Specifically, southward subduction of the Bangong-Nujiang Ocean lithosphere and subsequent slab rollback metasomatized the mantle wedge and the lithospheric mantle above, whose melting produced basaltic magmas. Underplating and intrusion of these basaltic magmas caused crustal melting and generation of granitoid magmas parental to the tonalite and enclaves we study