Breaking the 10% Efficiency Barrier in Organic Photovoltaics: Morphology and Device Optimization of Well‐Known PBDTTT Polymers

With the advances in organic photovoltaics (OPVs), the invention of model polymers with superior properties and wide applicability is of vital importance to both the academic and industrial communities. The recent inspiring advances in OPV research have included the emergence of poly(benzodithiophene‐co‐thieno[3,4‐b]thiophene) (PBDTTT)‐based materials. Through the combined efforts on PBDTTT polymers, over 10% efficiencies have been realized recently in various types of OPV devices. This review attempts to critically summarize the recent advances with respect to five well‐known PBDTTT polymers and their design considerations, basic properties, photovoltaic performance, as well as device application in conventional, inverted, tandem solar cells. These PBDTTT polymers also make great contributions to the rapid advances in the field of emerging ternary blends and fullerene‐free OPVs with top performances. Addtionally, new challenges in developing novel photovoltaic polymers with more superior properties are prospected. More importantly, the research of highly efficient PBDTTT‐based polymers provides useful insights and builds fundamentals for new types of OPV applications with various architectures.     

Advances in fundamental and applied studies in China of fungal biocontrol agents for use against arthropod pests

Entomopathogenic fungi, such as Beauveria bassiana and Metarhizium anisopliae, are environmentally friendly biocontrol agents (BCAs) against various arthropod pests. We provide an overview to the past-decade advances in fungal BCA research and application in China. Since 1960s, fungal BCAs have been mass-produced for application and at present, thousands of tons of their formulations are annually applied to control forest, agricultural, greenhouse and grassland insect pests throughout the country. Apart from technical advances in mass production, formulation and application of fungal BCAs, basic studies on the genomics, molecular biology, genetic engineering and population genetics of fungal entomopathogens have rapidly progressed in the past few years in China. The completed genomic studies of M. anisopliae, Metarhizium acridum, B. bassiana and Cordyceps militaris provide profound insights into crucial gene functions, fungal pathogenesis, host–pathogen interactions and mechanisms involved in fungal sexuality. New knowledge gained from the basic studies has been applied to improve fungal virulence and stress tolerance for developing more efficacious and field-persistent mycoinsecticides by means of microbial biotechnology, such as genetic engineering. To alleviate environmental safety concerns, more efforts are needed to generate new data not only on the effects of engineered BCAs on target and non-target arthropods but also on their potential effects on gene flow and genetic recombination before field release.     

Aortic valve disease in diabetes: Molecular mechanisms and novel therapies

Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non-diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic-hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes-induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD.     

Active and machine learning-based approaches to rapidly enhance microbial chemical production

In order to make renewable fuels and chemicals from microbes, new methods are required to engineer microbes more intelligently. Computational approaches, to engineer strains for enhanced chemical production typically rely on detailed mechanistic models (e.g., kinetic/stoichiometric models of metabolism)—requiring many experimental datasets for their parameterization—while experimental methods may require screening large mutant libraries to explore the design space for the few mutants with desired behaviors. To address these limitations, we developed an active and machine learning approach (ActiveOpt) to intelligently guide experiments to arrive at an optimal phenotype with minimal measured datasets. ActiveOpt was applied to two separate case studies to evaluate its potential to increase valine yields and neurosporene productivity in Escherichia coli. In both the cases, ActiveOpt identified the best performing strain in fewer experiments than the case studies used. This work demonstrates that machine and active learning approaches have the potential to greatly facilitate metabolic engineering efforts to rapidly achieve its objectives.     

Redox regulation of plant stem cell fate

Despite the importance of stem cells in plant and animal development, the common mechanisms of stem cell maintenance in both systems have remained elusive. Recently, the importance of hydrogen peroxide (H₂O₂) signaling in priming stem cell differentiation has been extensively studied in animals. Here, we show that different forms of reactive oxygen species (ROS) have antagonistic roles in plant stem cell regulation, which were established by distinct spatiotemporal patterns of ROS‐metabolizing enzymes. The superoxide anion () is markedly enriched in stem cells to activate WUSCHEL and maintain stemness, whereas H₂O₂ is more abundant in the differentiating peripheral zone to promote stem cell differentiation. Moreover, H₂O₂ negatively regulates biosynthesis in stem cells, and increasing H₂O₂ levels or scavenging leads to the termination of stem cells. Our results provide a mechanistic framework for ROS‐mediated control of plant stem cell fate and demonstrate that the balance between and H₂O₂ is key to stem cell maintenance and differentiation.     

Development of cytochrome b558 and oxidative metabolism in human granulocytes, monocytes and during differentiation of HL-60 and U 937 cells

The development of cytochrome b558 (Cyt b) as determined spectrophotometrically, was investigated in human polymorphonuclear neutrophils (PMN), monocytes (MN) and during differentiation of HL-60 and U 937 cells induced by retinoic acid (RA) alone or in combination with IFN gamma. O2- release in response to a panel of stimulating agents, ie latex particles, opsonised zymosan, PMA, Con A and fMLP, was monitored by lucigenin-amplified chemiluminescence (CL). In parallel the expression of myeloperoxidase (MPO) was investigated and its catalytic activity on H2O2 related to luminol-amplified CL responses. In mature PMN and MN phagocytes, regardless of the stimulating agent, the O2- production is closely related to Cyt b but not to MPO specific contents. In differentiated HL-60 and U 937 cells, the oxidative metabolism increases in parallel with Cyt b specific contents, both being enhanced by the addition of IFN gamma to the RA treatment. However, marked differences in the O2- production intensities are observed depending on the stimulating agent tested and the state of differentiation considered. The PMA-stimulated O2- production is rather low ie 100 and 20 times less in granulocytic HL-60 and monocyto-macrophagic U 937 cells than in PMN and MN respectively. Latex, zymosan and Con A stimulated responses are close to those of MN, in monocyte-macrophagic U 937 cells. In conclusion, these data show that during differentiation; 1), Cyt b plays a critical role in O2- production; 2), the pathways leading to NADPH oxidase activation are diversely modulated following phagocyte differentiation with IFN gamma and/or with RA.     

l-Malic Acid Fermentation by Mixed Culture of Rhizopus arrhizus and Proteus vulgaris

When Rhizopus arrhizus NRRL 1526 was mix-cultured with Proteus vulgaris AHU 1144, a strain having a high fumarase activity, in a medium containing glucose as a substrate, fumaric acid fermentation was successively converted to l-malic acid fermentation and large amounts of l-malic acid were accumulated as an end product.

As an inoculum of P. vulgaris for this fermentation, cells in the stationary growth phase (48 to 72 hr culture) were much more favorable than those in the exponential growth phase (18 hr culture) and malic acid yields in the former case were as high as about 70 to 75 % based on initial glucose after 3 to 4 days of the mixed culture.