Effects of orientational and positional randomness of particles on photonic band gap

A recent work [PRL, 126, 208002 (2021)] has explored how thermal noise-induced randomness in a self-assembled photonic crystal affects photonic band gaps (PBGs). For the system of a two-dimensional photonic crystal composed of a self-assembled array of rods with square cross sections, it was found that its PBGs can exist over an extensive range of packing densities. Counterintuitively, at intermediate packing densities, the transverse magnetic (TM) band gap of the self-assembled system can be larger than that of its corresponding perfect system (rods arranged in a perfect square lattice and having identical orientations). Due to shape anisotropicity, the randomness in the self-assembled system contains two kinds of randomness, i.e., positional and orientational randomness of the particles. In this work, we further investigate how PBGs are influenced solely by positional or orientational randomness. We find that compared to the perfect situation, the introduction of only orientational randomness decreases the transverse electric (TE) band gap while having no obvious effects on the transverse magnetic (TM) band gap. In contrast, the introduction of only positional randomness decreases the TE band gap significantly, while it can widen or narrow the TM band gap, depending on the parameter range. We also discuss the thermal (i.e., self-assembled) system where two kinds of randomness are present. Our study contributes to a better understanding of the role orientational randomness and positional randomness play on PBGs, and may benefit the PBG engineering of photonic crystals through self-assembly approaches

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Covalent Bonding Aptamer with Enhanced SARS-CoV-2 RBD-ACE2 Blocking and Pseudovirus Neutralization Activities

SARS-CoV-2 uses its spike protein receptor-binding domain (RBD) to interact with the angiotensin-converting enzyme 2 (ACE2) receptor on host cells. Inhibitors of the RBD-ACE2 interaction are therefore promising drug candidates in treating COVID-19. Here, we report a covalent bonding aptamer that can block the RBD-ACE2 interaction and neutralize SARS-CoV-2 pseudovirus infection by forming covalent bonds on RBD, resulting in more than 25-fold enhancement of pseudovirus neutralization efficacy over the original binding aptamer. The chemically modified aptamer is equipped with sulfur(VI) fluoride exchange (SuFEx) modifications and covalently targets important RBD residues within the RBD-ACE2 binding interface, including Y453 and R408. The covalent bonding is highly specific to RBD over other proteins such as human serum albumin (HSA), ACE2 and immunoglobulin G1 (IgG1) Fc. Our study demonstrates the promise of introducing covalent inhibition mechanisms for developing robust RBD-ACE2 inhibitors against SARS-CoV-2 infection

Changes and continuity in pottery production and use at Wujiafentou in the core zone of Youziling and Shijiahe cultures in central China

Abstract The Wujiafentou site is located at the heart of the Youziling (5900–5500 cal BP) and Shijiahe (4500–4200 cal BP) cultures in the Handong region, a core area to understand the relationship among economic networks, sociopolitical integration, and regional identity in the middle Yangtze River valley (MYRV) of central China during the Late Neolithic times. Its pottery assemblages are important clues to understanding the pottery production and use before and after the extensive walled town construction activities in the Neolithic MYRV. Wujiafentou is less than 5 km from the Shijiahe walled town, the largest city of its time in the MYRV. This paper applies microscopic examination and chemical and mineralogical analyses to a sample of 152 sherds of the Youziling-period and Shijiahe-period utilitarian vessels unearthed from the Wujiafentou site, revealing the changes and continuity in pottery production and use over time. We also probe into the socio-economic ties between Wujiafentou and the Shijiahe walled town mainly through hong tao bei (red clay cups), which were widely distributed and presumably highly symbolic items of the Shijiahe culture related to drinking, feasts, and rituals. We propose that the Wujiafentou inhabitants produced their red clay cups by mimicking those made within the Shijiahe walled town. Our study highlights an alternative interpretation of the formation of a regional identity during the Shijiahe period

Investigation of Using Calcined Coal Gangue as the Co-Blended Precursor in the Alkali-Activated Metakaolin

The feasibility and performance of using calcined coal gangue (CCG) to substitute metakaolin (MK) as the precursor to prepare alkali-activated materials (AAMs) were thoroughly evaluated by conducting combined experiments of flowability test, mechanical measurement, calorimetry and microstructure analysis, etc. It was found that the increased substitution ratio of CCG to MK can increase the flowability of the prepared paste by up to 28.1% and decrease its viscosity by up to 55.8%. In addition, a prolonged setting time of up to 31.8% was found with the increased substitution amount of CCG to MK, which can be attributed to the low reactivity of CCG compared to that of MK. Lastly, even though the presence of CCG can lead to a decrease in the early compressive strength of the hardened paste, a highly recovered long-term mechanical property can be found due to the continuous reaction of CCG. All of these results prove the feasibility of using CCG as one co-blended precursor with MK to prepare alkali-activated materials

Comparative study on thermally evaporated and solution processed cathode modifying layers in organic solar cells

Organic solar cells have been fabricated using cathode modifying layers of thermally evaporated bathophenanthroline (Bphen), ytterbium doped Bphen (Bphen:Yb), and solution processed (N,N-dimethyl-ammonium N-oxide)propyl perylene diimide (PDINO). Compared to pristine Bphen, Bphen:Yb shows higher electron mobility and thereby increases fill factor of device, demonstrating the weak n-doping of Yb in Bphen. As a result of Fermi level pinning, Bphen:Yb forms an ohmic contact with photoactive layer, underpinning efficient electron transport and extraction of device. Compared to conventional PDINO, despite lower electron mobility, Bphen:Yb enables increased optical absorption of device and smoother morphology of device, thereby improving power conversion efficiency of device. The current research points out that the integration of thermally evaporated weakly n-doped cathode modifying layer and solution processed photoactive layer is a promising method to fabricate high-efficiency and low-cost organic solar cells

Characterization and Functional Analysis of <i>PmCMK</i>: A Gene Involved in Terpenoid Synthesis in <i>Pinus massoniana</i>

In Pinus massoniana, the methyl-D-erythritol-4-phosphate (MEP) pathway plays a crucial role in the biosynthesis of terpenoids. The fourth step of this pathway is specifically regulated by 4-(cytidine 5′-diphospho)-2-C-methyl-D-erythritol kinase (CMK). In this study, PmCMK (MW892445.1) was isolated. As a member of the GHMP kinase family, PmCMK exhibits homology with CMK genes across diverse species. The examination of relative expression patterns revealed that PmCMK exhibited higher expression levels in tissues of P. massoniana that are rich in resin. We successfully cloned the PmCMK promoter (1654 bp) and integrated it into a GUS reporter vector. This construct was then transformed into the leaves of tobacco (Nicotiana × sanderae) to assess transient expression patterns. The results demonstrated that the promoter was active not only in the roots, leaves, and stems of the tobacco plants but also exhibited varying expression levels in response to treatments with IAA, SA, MeJA, and PEG6000. This suggested that PmCMK expression was modulated by a variety of signals. It revealed that the expression of PmCMK was affected by different treatments. Further allogeneic expression studies showed that tobacco overexpressing PmCMK exhibited increased levels of chlorophyll and carotene compared to the wild type. This enhancement in content indicates that PmCMK has a significant role in isoprene biosynthesis. These findings provide valuable insights for future research aimed at elucidating the biosynthetic pathways of terpenoids and developing breeding strategies to enhance resin production in P. massoniana

Acupuncture for Parkinson’s Disease: Efficacy Evaluation and Mechanisms in the Dopaminergic Neural Circuit

Parkinson’s disease (PD) is a chronic and progressive neurodegenerative disease caused by degeneration of dopaminergic neurons in the substantia nigra. Existing pharmaceutical treatments offer alleviation of symptoms but cannot delay disease progression and are often associated with significant side effects. Clinical studies have demonstrated that acupuncture may be beneficial for PD treatment, particularly in terms of ameliorating PD symptoms when combined with anti-PD medication, reducing the required dose of medication and associated side effects. During early stages of PD, acupuncture may even be used to replace medication. It has also been found that acupuncture can protect dopaminergic neurons from degeneration via antioxidative stress, anti-inflammatory, and antiapoptotic pathways as well as modulating the neurotransmitter balance in the basal ganglia circuit. Here, we review current studies and reflect on the potential of acupuncture as a novel and effective treatment strategy for PD. We found that particularly during the early stages, acupuncture may reduce neurodegeneration of dopaminergic neurons and regulate the balance of the dopaminergic circuit, thus delaying the progression of the disease. The benefits of acupuncture will need to be further verified through basic and clinical studies