Machine learning studies automatic algorithms that improve themselves through experience. It is widely used for analyzing and extracting value from large biomedical data sets, or “big biomedical ...data,” advancing biomedical research, and improving healthcare. Before a machine learning model is trained, the user of a machine learning software tool typically must manually select a machine learning algorithm and set one or more model parameters termed hyper-parameters. The algorithm and hyper-parameter values used can greatly impact the resulting model’s performance, but their selection requires special expertise as well as many labor-intensive manual iterations. To make machine learning accessible to layman users with limited computing expertise, computer science researchers have proposed various automatic selection methods for algorithms and/or hyper-parameter values for a given supervised machine learning problem. This paper reviews these methods, identifies several of their limitations in the big biomedical data environment, and provides preliminary thoughts on how to address these limitations. These findings establish a foundation for future research on automatically selecting algorithms and hyper-parameter values for analyzing big biomedical data.
The enhancement of non-uniformly illuminated images often suffers from over-enhancement and produces unnatural results. This paper presents a naturalness preserved enhancement method for ...non-uniformly illuminated images, using a priori multi-layer lightness statistics acquired from high-quality images. This paper makes three important contributions: designing a novel multi-layer image enhancement model; deriving the multi-layer lightness statistics of high-quality outdoor images, which are incorporated into the multi-layer enhancement model; and showing that the overall quality rating of enhanced images is consistent with a combination of contrast enhancement and naturalness preservation. Two separate human observer evaluation studies were conducted on naturalness preservation and overall image quality. The results showed the proposed method outperformed four compared state-of-the-art enhancement methods.
A quinoline-linked and ionic liquid-decorated covalent organic framework was prepared by incorporation of a multicomponent Povarov reaction and postsynthetic modification. The imidazolium and ...sulfonic acid-decorated COF-IM-SO3H can be a highly efficient Brønsted acid catalyst to promote the Biginelli reaction under solvent-free conditions in a heterogeneous way. In addition, a scaled-up Biginelli reaction has been readily realized over a COF-IM-SO3H@chitosan aerogel-based cup reactor.
Polyethylene film is the most widely used plastic film in agricultural production activities, and its depolymerization products are mainly polyethylene-particles (PE-particles) of different molecular ...weights. However, the impact of the molecular weights of the PE-particles on soil-crop microenvironment has not been elucidated. In this study, a potted microcosmic simulation system was used to evaluate the impact of low, medium and high molecular weight PE-particles on soil metabolism, microbial community structure, and crop growth. There were obvious differences in the shape and surface microstructure of PE-particles with different molecular weights. Soil sucrase and peroxidase had significant responses to PE-particles of different molecular weights. In the rhizosphere, the number of microorganisms and the microbial alpha diversity index increased with increasing PE-particles molecular weight. Rhizobacter, Nitrospira, and Sphingomonas were the dominant microorganisms induced by PE-particles to regulate the metabolism of elements. Carbohydrate and amino acid contents in rhizosphere soils were the key factors affecting the species abundance of Lysobacter, Polyclovorans, Rhizobacter, and Sphingomonas. In plants, PE-particles treatment reduced the plant biomass and photosynthetic rate and disrupted normal mineral nutrient metabolism. Different molecular weight PE-particles may therefore have adverse effects on the soil-plant system.
Display omitted
•Soil sucrase and peroxidase had significant responses to PE-particles of different molecular weights.•Microbial alpha diversity index gradually increased with increasing PE-particles molecular weight.•Carbohydrate and amino acid contents in the rhizosphere soil were the key factors affecting the species abundance.•PE-particles reduced plant biomass and photosynthetic rate and interfered with mineral nutrient metabolism.
Syngas is produced by thermal gasification of both nonrenewable and renewable sources including biomass and coal, and it consists mainly of CO, CO2, and H2. In this paper we aim to bioconvert CO in ...the syngas to CH4. A novel technology for simultaneous sewage sludge treatment and CO biomethanation in an anaerobic reactor was presented. Batch experiments showed that CO was inhibitory to methanogens, but not to bacteria, at CO partial pressure between 0.25 and 1 atm under thermophilic conditions. During anaerobic digestion of sewage sludge supplemented with CO added through a hollow fiber membrane (HFM) module in continuous thermophilic reactors, CO did not inhibit the process even at a pressure as high as 1.58 atm inside the HFM, due to the low dissolved CO concentration in the liquid. Complete consumption of CO was achieved with CO gas retention time of 0.2 d. Results from high-throughput sequencing analysis showed clear differences of the microbial community structures between the samples from liquid and biofilm on the HFM in the reactor with CO addition. Species close to Methanosarcina barkeri and Methanothermobacter thermautotrophicus were the two main archaeal species involved in CO biomethanation. However, the two species were distributed differently in the liquid phase and in the biofilm. Although the carboxidotrophic activities test showed that CO was converted by both archaea and bacteria, the bacterial species responsible for CO conversion are unknown.
Chronic wound infections resulting from severe bacterial invasion have become a major medical threat worldwide. Herein, we report a large-area, homogeneous, and self-standing porphyrin-covalent ...organic framework (COF)-based membrane with encapsulated ibuprofen (IBU) via an in situ interfacial polymerization and impregnation approach. The obtained IBU@DhaTph-membrane exhibits highly effective antibacterial and anti-inflammatory effects via synergistic light-induced singlet oxygen (
O
) generation and controllable IBU release, which is well supported by in vitro experiments. In addition, the IBU@DhaTph-membrane-based biocompatible "band-aid" type dressing is fabricated, and its excellent anti-infection and tissue remodeling activities are fully evidenced by in vivo chronic wound-healing experiments. This study may inspire and promote the fabrication of many more new types of COF-based multifunctional biomaterials for various skin injuries in clinical medicine.
A deep understanding on the crucial factors of the enhanced macroscopic second harmonic generation (SHG) in some deep‐ultraviolet nonlinear optical (NLO) materials is needed to design new NLO ...materials. Since an optical process relates to the electron excitation and polarization simultaneously, the instantaneous dipole moments and their structures in excitation should be seriously taken account to seek the principal factor in SHG response. In this work, we study the Ba4B11O20F (BBOF), a NLO material, by using the orbital projection technique. From the projected SHG of our theoretic calculation, we recognize the principal dipole moment of the dominant influence on SHG and the relevant atom groups between which the dipole moment is accommodated. With the conclusion that the dipole moment with the most significant influence on SHG is the one between the oxygen–boron polyhedral anion group and barium cation, we predict that Ba4Al11O20F (BAOF) has a comparable SHG response.
In the NLO materials reported herein, an electron transits from the oxygen atom of the valence state to the barium atom of the conduction state caused by the optical excitation. The charge transition generates instantaneous spatial dipole moments, which contribute to the projected SHG. Depending on the arrangement and ambience of the dipole moments, all microscopic SHG integrate into the macroscopic SHG response.
Methanation of propionate requires syntrophic interaction of propionate-oxidizing bacteria and hydrogenotrophic methanogens, which is referred to as interspecies electron transfer. The present study ...showed that 10 mg/L conductive magnetite enhanced the methane production rate from propionate by around 44% in batch experiments, and both direct interspecies electron transfer and interspecies H2 transfer were thermodynamically feasible with the addition of magnetite. The methanation of propionate facilitated by magnetite was also demonstrated in a long-term operated continuous reactor. The methane production rate from acetate by the enriched mixed culture with magnetite was higher than that without magnetite, while similar methane production rates were found from H2/CO2 by the enriched mixed culture with and without magnetite. The ability to utilize molecular H2 indicated interspecies H2 transfer played a role in the enriched culture with magnetite, and propionate-oxidizing bacteria relating with interspecies H2 transfer were also detected by metagenomic sequencing. Metagenomic sequencing analysis also showed that Thauera, possibly relating with direct interspecies electron transfer, were enriched with the addition of magnetite. iTRAQ quantitative proteomic analysis, which was used in mixed culture for the first time, showed that magnetite induced the changes of protein expression levels involved in various pathways during the methanation of propionate. The up-regulation of proteins involved in propionate metabolism were found, and they were mainly originated from propionate-oxidizing bacteria which were not reported to be capable of direct interspecies electron transfer until now. Cytochrome c oxidase was also revealed as the possible protein relating with direct interspecies electron transfer considering its up-regulation with the addition of magnetite and origination from Thauera. Most of the up-regulated proteins in methane metabolism were originated from Methanosaeta, while most of the enzymes with down-regulated proteins were originated from Methanosarcina. However, the up-regulated proteins relating with hydrogenotrophic methanogenesis were originated from neither Methanosaeta nor Methanosarcina, indicating they were not involved in direct interspecies electron transfer. The hydrogenotrophic methanogens, e.g. Methanospirillum, Methanosphaerula et al., might be involved in direct interspecies electron transfer. Overall, the present study showed that both direct interspecies electron transfer and interspecies H2 transfer were present during methanation of propionate facilitated by magnetite.
Display omitted
•Enhanced methane production rate from propionate with the addition of magnetite.•iTRAQ quantitative proteomic analysis was used to reveals the changes of pathways.•Propionate was degraded via both DIET and IHT with the addition of magnetite.
In situ biogas upgrading was conducted by introducing H
2
directly to the anaerobic reactor. As H
2
addition is associated with consumption of the CO
2
in the biogas reactor, pH increased to higher ...than 8.0 when manure alone was used as substrate. By co-digestion of manure with acidic whey, the pH in the anaerobic reactor with the addition of hydrogen could be maintained below 8.0, which did not have inhibition to the anaerobic process. The H
2
distribution systems (diffusers with different pore sizes) and liquid mixing intensities were demonstrated to affect the gas-liquid mass transfer of H
2
and the biogas composition. The best biogas composition (75:6.6:18.4) was obtained at stirring speed 150 rpm and using ceramic diffuser, while the biogas in the control reactor consisted of CH
4
and CO
2
at a ratio of 55:45. The consumed hydrogen was almost completely converted to CH
4
, and there was no significant accumulation of VFA in the effluent. The study showed that addition of hydrogen had positive effect on the methanogenesis, but had no obvious effect on the acetogenesis. Both hydrogenotrophic methanogenic activity and the concentration of coenzyme F
420
involved in methanogenesis were increased. The archaeal community was also altered with the addition of hydrogen, and a
Methanothermobacter thermautotrophicus
related band appeared in a denaturing gradient gel electrophoresis gel from the sample of the reactor with hydrogen addition. Though the addition of hydrogen increased the dissolved hydrogen concentration, the degradation of propionate was still thermodynamically feasible at the reactor conditions.
PDF
