Photonic-assisted wideband microwave frequency measurement based on optical heterodyne detection.

A photonic-assisted microwave frequency measurement (MFM) method based on optical heterodyne detection is proposed and experimentally demonstrated. In the proposed MFM system, a linearly chirped optical waveform (LCOW) from a three-electrode distributed Bragg reflector laser diode (DBR-LD) and a multi-wavelength signal from a Mach-Zehnder modulator (MZM), where the signal under test (SUT) is modulated on an optical carrier from a distributed feedback laser diode (DFB-LD), are heterodyne detected by the photodetector (PD). A bandpass filter then filters the detected signal, and the envelope is detected by an oscilloscope. Then, frequency-to-time mapping is realized, and the signal frequency is measured. Thanks to the fast tuning rate and large tuning range of the DBR-LD, the proposed MFM system has a high measurement speed and a broad instantaneous measurement bandwidth. In the experimental demonstration, a measurement error below 39.1 MHz is achieved at an instantaneous bandwidth of 20 GHz and a measurement speed of 1.12 GHz/µs. The MFM of a frequency-hopping signal is also experimentally demonstrated. The successful demonstration of the MFM system with a simple structure provides a new optical solution for realizing broadband and fast microwave frequency measurements.

CRISPR/Cas13a-based single-nucleotide polymorphism detection for reliable determination of ABO blood group genotypes.

The ABO blood group plays an important role in blood transfusion, linkage analysis, individual identification, etc. Serologic methods of blood typing are gold standards for the time being, which require stable typing antisera and fresh blood samples and are labor intensive. At present, reliable determination of ABO blood group genotypes based on single-nucleotide polymorphisms (SNPs) among A, B, and O alleles remains necessary. Thus, in this work, CRISPR/Cas13a-mediated genotyping for the ABO blood group by detecting SNPs between different alleles was proposed. The ABO*O.01.01(c.261delG) allele (G for the A/B allele and del for the O allele) and ABO*B.01(c.796C > A) allele (C for the A/O allele and A for the B allele) were selected to determine the six genotypes (AA, AO, BB, BO, OO, and AB) of the ABO blood group. Multiplex PCR was adapted to simultaneously amplify the two loci. CRISPR/Cas13a was then used to specifically differentiate ABO*O.01.01(c.261delG) and ABO*B.01(c.796C > A) of A, B, and O alleles. Highly accurate determination of different genotypes was achieved with a limit of detection of 50 pg per reaction within 60 min. The reliability of this method was further validated based on its applicability in detecting buccal swab samples with six genotypes. The results were compared with those of serological and sequencing methods, with 100% accuracy. Thus, the CRISPR/Cas13a-mediated assay shows great application potential in the reliable identification of ABO blood group genotypes in a wide range of samples, eliminating the need to collect fresh blood samples in the traditional method.

Multiple Physiological and Biochemical Functions of Ascorbic Acid in Plant Growth, Development, and Abiotic Stress Response.

Ascorbic acid (AsA) is an important nutrient for human health and disease cures, and it is also a crucial indicator for the quality of fruit and vegetables. As a reductant, AsA plays a pivotal role in maintaining the intracellular redox balance throughout all the stages of plant growth and development, fruit ripening, and abiotic stress responses. In recent years, the de novo synthesis and regulation at the transcriptional level and post-transcriptional level of AsA in plants have been studied relatively thoroughly. However, a comprehensive and systematic summary about AsA-involved biochemical pathways, as well as AsA's physiological functions in plants, is still lacking. In this review, we summarize and discuss the multiple physiological and biochemical functions of AsA in plants, including its involvement as a cofactor, substrate, antioxidant, and pro-oxidant. This review will help to facilitate a better understanding of the multiple functions of AsA in plant cells, as well as provide information on how to utilize AsA more efficiently by using modern molecular biology methods.

Ultrafast Early Warning of Heart Attacks through Plasmon-Enhanced Raman Spectroscopy using Collapsible Nanofingers and Machine Learning.

As the leading cause of death, heart attacks result in millions of deaths annually, with no end in sight. Early intervention is the only strategy for rescuing lives threatened by heart disease. However, the detection time of the fastest heart-attack detection system is >15 min, which is too long considering the rapid passage of life. In this study, a machine learning (ML)-driven system with a simple process, low-cost, short detection time (only 10 s), and high precision is developed. By utilizing a functionalized nanofinger structure, even a trace amount of biomarker leaked before a heart attack can be captured. Additionally, enhanced Raman profiles are constructed for predictive analytics. Five ML models are developed to harness the useful characteristics of each Raman spectrum and provide early warnings of heart attacks with >98% accuracy. Through the strategic combination of nanofingers and ML algorithms, the proposed warning system accurately provides alerts on silent heart-attack attempts seconds ahead of actual attacks.

Activities of daily living predict periprocedural myocardial infarction and injury following percutaneous coronary intervention: a cross-sectional study.

BACKGROUND: In recent years, there has been growing interest in exploring the relationship between activities of daily living (ADL) and cardiovascular diseases. This retrospective cross-sectional study aimed to investigate the association of ADL measured by Barthel index (BI) with periprocedural myocardial infarction (PMI) and injury following percutaneous coronary intervention (PCI). METHODS: Enrolled patients were stratified into impaired and unimpaired ADL groups according to their BI scores. Logistic regressions were conducted to explore the association of ADL on admission with periprocedural myocardial injury and infarction. Restricted cubic spline (RCS) curve and subgroup analysis were also performed. RESULTS: Totally, 16.4% of patients suffered from PMI; the mean age was 65.8 ± 10.4 years old. RCS analysis showed that the morbidity of periprocedural myocardial infarction and injury showed a downward tendency with increasing BI scores. Multivariable logistic regression analysis demonstrated that impaired ADL was an independent risk factor for periprocedural myocardial infarction (OR = 1.190, 95% CI [1.041, 1.360], P = 0.011) and injury (OR = 1.131, 95% CI [1.017, 1.257], P = 0.023). Subgroup analysis showed that the association between ADL and PMI was founded in several subgroups, while the association between ADL and periprocedural myocardial injury was founded only in BMI ≥ 24 kg/m2 subgroup. CONCLUSION: Impaired ADL at hospital admission was an independent risk factor for periprocedural myocardial infarction and injury among patients following PCI.

The Ubiquitin-26S Proteasome Pathway and Its Role in the Ripening of Fleshy Fruits.

The 26S proteasome is an ATP-dependent proteolytic complex in eukaryotes, which is mainly responsible for the degradation of damaged and misfolded proteins and some regulatory proteins in cells, and it is essential to maintain the balance of protein levels in the cell. The ubiquitin-26S proteasome pathway, which targets a wide range of protein substrates in plants, is an important post-translational regulatory mechanism involved in various stages of plant growth and development and in the maturation process of fleshy fruits. Fleshy fruit ripening is a complex biological process, which is the sum of a series of physiological and biochemical reactions, including the biosynthesis and signal transduction of ripening related hormones, pigment metabolism, fruit texture changes and the formation of nutritional quality. This paper reviews the structure of the 26S proteasome and the mechanism of the ubiquitin-26S proteasome pathway, and it summarizes the function of this pathway in the ripening process of fleshy fruits.

An integrated fluorescent lateral flow assay for multiplex point-of-care detection of four respiratory viruses.

This work established a highly sensitive and specific quantum dot nanobeads-based lateral flow assay for multiplex detection of four respiratory virus markers at point of care. The respiratory virus antigens were detected by fluorescent lateral flow strips within 20 min. The limits of detection for SARS-CoV-2 antigen, IAV antigen, IBV antigen, and ADV antigen were 0.01 ng/mL, 0.05 ng/mL, 0.31 ng/mL, and 0.40 ng/mL, respectively, which were superior to that of conventional AuNPs-based colorimetric lateral flow assay. The coefficients of variation of the test strip were 6.09%, 2.24%, 7.92%, and 12.43% for these four antigens, which indicated that the proposed method had good repeatability. The specificity of the detection system was verified by different combinations of these four respiratory viruses and several other respiratory pathogens. These results indicated that this method could simultaneously detect SARS-CoV-2, IAV, IBV and ADV in a short assay time, showing the remarkable potential for the rapid and multiplex detection of respiratory viruses in resource-limited settings.

Molecular and Genetic Events Determining the Softening of Fleshy Fruits: A Comprehensive Review.

Fruit softening that occurs during fruit ripening and postharvest storage determines the fruit quality, shelf life and commercial value and makes fruits more attractive for seed dispersal. In addition, over-softening results in fruit eventual decay, render fruit susceptible to invasion by opportunistic pathogens. Many studies have been conducted to reveal how fruit softens and how to control softening. However, softening is a complex and delicate life process, including physiological, biochemical and metabolic changes, which are closely related to each other and are affected by environmental conditions such as temperature, humidity and light. In this review, the current knowledge regarding fruit softening mechanisms is summarized from cell wall metabolism (cell wall structure changes and cell-wall-degrading enzymes), plant hormones (ETH, ABA, IAA and BR et al.), transcription factors (MADS-Box, AP2/ERF, NAC, MYB and BZR) and epigenetics (DNA methylation, histone demethylation and histone acetylation) and a diagram of the regulatory relationship between these factors is provided. It will provide reference for the cultivation of anti-softening fruits.

Relationships between genome methylation, levels of non-coding RNAs, mRNAs and metabolites in ripening tomato fruit.

Ripening of tomato fruit is a complex tightly orchestrated developmental process that involves multiple physiological and metabolic changes that render fruit attractive, palatable and nutritious. Ripening requires initiation, activation and coordination of key pathways at the transcriptional and post-transcriptional levels that lead to ethylene synthesis and downstream ripening events determining quality. We studied wild-type, Gr and r mutant fruits at the coding and non-coding transcriptomic, metabolomic and genome methylation levels. Numerous differentially expressed non-coding RNAs were identified and quantified and potential competing endogenous RNA regulation models were constructed. Multiple changes in gene methylation were linked to the ethylene pathway and ripening processes. A combined analysis of changes in genome methylation, long non-coding RNAs, circular RNAs, micro-RNAs and fruit metabolites revealed many differentially expressed genes (DEGs) with differentially methylated regions encoding transcription factors and key enzymes related to ethylene or carotenoid pathways potentially targeted by differentially expressed non-coding RNAs. These included ACO2 (targeted by MSTRG.59396.1 and miR396b), CTR1 (targeted by MSTRG.43594.1 and miR171b), ERF2 (targeted by MSTRG.183681.1), ERF5 (targeted by miR9470-3p), PSY1 (targeted by MSTRG.95226.7), ZISO (targeted by 12:66127788|66128276) and NCED (targeted by MSTRG.181568.2). Understanding the functioning of this intricate genetic regulatory network provides new insights into the underlying integration and relationships between the multiple events that collectively determine the ripe phenotype.

Stretchable optical diffraction grating from poly(acrylic acid)/polyethylene oxide stereocomplex.

Advances in optical materials, which were initially static elements, have enabled dynamically tunable optical diffraction gratings to be designed. One common tuning strategy relies on mechanical deformation of the grating pitch to modify the diffraction pattern. In the present work, we demonstrate an all-polymer tunable diffraction grating fabricated using a modified replica molding process. The poly(acrylic acid) (PAA)/polyethylene oxide (PEO) polymer stereocomplex films exhibit optical transmittance at or above 80% from 500 nm to 1400 nm and stretchability over 800% strain with reversibility under 70% strain. The imprinted gratings are characterized at 633 nm and 1064 nm under a range of strain conditions. The measured tunability agrees with finite element method modeling.

SRNAome and transcriptome analysis provide insight into strawberry fruit ripening.

Strawberry fruit ripening is a complex process affected by multiple factors at different regulation levels. To elucidate the regulation mechanisms, the combined analysis of sRNAome and transcriptome were used. A total of 124 known and 190 novel miRNAs were found, 62 of them were significantly differentially expressed (DE). The targets of the DE miRNAs were parsed and several TFs, such as SPL, ARF, WRKY, and TCP, were found to be involved in ripening. Elevated CO2 can significantly postpone ripening and miR156, miR166f, miR171a, and miR171d were the DE miRNAs. Transcriptome analysis found 313 DE genes related to fruit ripening, including cell wall metabolism-related genes, color-related genes, ethylene-related genes, and genes encoding TFs such as MYB, SPL, NAC, TCP, and ARF. Based on above, a combined regulatory model involved in fruit ripening was created. These results provide valuable information for understanding the complicated coordinated regulatory network of strawberry fruit ripening.

Effect of 1-MCP and ethylene absorbent on the development of lenticel disorder of 'Xinli No.7' pear and possible mechanisms.

BACKGROUD: A common lenticel disorder which occurs in the peel of 'Xinli No. 7' pears (Pyrus bretschneideri Rehd.) had not previously been described. Symptoms of this lenticel disorder include enlarging and bulging of the lenticels which results in significant commercial losses. Understanding the physiological basis of lenticel disorder and developing practical methods to control it is crucial for the successful marketing of this pear. RESULTS: The development of this lenticel disorder was found to be closely related to the endogenous ethylene production during storage. 1-Methylcyclopropene (1-MCP) combined with an ethylene absorbent (EA) treatment was found to significantly reduce the development of the disorder by inhibiting the expression of ethylene related genes, PbACS1, PbACS2 and PbACO. It is proposed that the enlarged lenticels may result from increased lignin accumulation in the peel cells, which is inhibited by this combined postharvest treatment. It was shown that the expression of six lignin related genes decreased following the treatment. The results suggest that PbPAL, Pb4CL and PbCAD could be critical in regulating the development of this lenticel disorder. CONCLUSION: Endogenous ethylene plays a key role in the development of this lenticel disorder in 'Xinli No. 7' pear. The enlarged lenticels which is characteristic of this disorder maybe related to increased lignin accumulation in the peel cells, which were inhibited with 1-MCP combined with an EA treatment. These results provide a practical method for managing the development of lenticel disorder in 'Xinli No. 7' pear and helps clarify the developmental mechanisms of this disorder. © 2020 Society of Chemical Industry.

Phase locking and homodyne detection of repetitive laser pulses.

A method to realize pulse laser phase locking and homodyne detection is proposed, which can be used in lidar and continuous variable quantum key distribution (CVQKD) systems. Theoretical analysis shows that homodyne detection of pulse laser has a sensitivity advantage of more than 4 dB over heterodyne detection. An experimental verification setup was constructed to realize phase-locking and homodyne detection of pulse lasers at repetition rates from 50 kHz to 2.4 MHz. For 320 ns signal laser pulses at 300 kHz with peak power of -65 dBm, the phase error is 8.9° (mainly limited by the chirp effect in the modulation of signal laser), and the detection signal-to-noise ratio reaches 20.2 dB. When the peak power is reduced to -75 dBm, phase locking and homodyne detection can still be achieved. Homodyne detection based on phase locking could serve as a novel weak-laser-pulse receiving method with high sensitivity and anti-interference performance.

Dispersion independent long-haul photon-counting optical time-domain reflectometry.

Photon-counting optical time-domain reflectometry (PC-OTDR) based on single photon detection is an effective scheme to attain the high spatial resolution for optical fiber fault monitoring. Currently, due to the spatial resolution of PC-OTDR being proportional to the pulse width of a laser beam, short laser pulses are essential for a high spatial resolution. However, short laser pulses have a large bandwidth, which would be widened by the dispersion of fiber, causing inevitable deterioration in the spatial resolution, especially for long-haul fiber links. In this Letter, we propose a scheme of dispersion independent PC-OTDR based on an infinite backscatter technique. Our experimental results-with more than 45 km long fiber-show that the spatial resolution of the PC-OTDR system is independent with the total dispersion of the fiber under test. Our method provides an avenue for developing long-haul PC-OTDR with high performance.

Noncoding RNAs: functional regulatory factors in tomato fruit ripening.

Tomato has emerged as the model system for investigations into the regulation of fleshy-fruit ripening and senescence, and the ripening process involving the coordinated regulation at the gene/chromatin/epigenetic, transcriptional, post-transcriptional and protein levels. Noncoding RNAs play important roles in fruit ripening as important transcriptional and post-transcriptional regulatory factors. In this review, we systematically summarize the recent advances in the regulation of tomato fruit ripening involved in ethylene biosynthesis and signal transduction, fruit pigment accumulation, fruit flavor and aroma, fruit texture by noncoding RNAs and their coordinate regulatory network model were set up and also suggest future directions for the functional regulations of noncoding RNAs on tomato fruit ripening.

Integrated waveguide true time delay beamforming system based on an SOI platform for 28 GHz millimeter-wave communication.

In this paper, we propose an on-chip waveguide beamforming system for a 28 GHz millimeter-wave signal based on silicon-on-insulator (SOI) technology. The system consists of four true time delay (TTD) lines, each of which consists of nine Bragg gratings with different periods. The minimum period of the grating is 312 nm, and the maximum period is 344 nm. By optimizing the position of the Bragg grating in the adjacent TTD lines, a time delay difference can be generated between the adjacent channels. By adjusting the operation wavelength of the optical carrier, the TTD lines can provide 9 different beamforming direction angles from -60∘ to 60° when the direction angular resolution is 15°. This proposed system has a useful application prospect in the phased array antennas of millimeter-wave communication.

Cadmium exposure affects growth performance, energy metabolism, and neuropeptide expression in Carassius auratus gibelio.

Cadmium (Cd) is the most abundant heavy metal in aquatic environments and is easily detected on a global scale. Carassius auratus gibelio is a common aquaculture species. The aim of this study was to explore the toxic effects of 1, 2, and 4 mg/L Cd on the energy metabolism, growth performance, and neurological responses of C. gibelio. After 30 days of exposure, Cd concentrations in the liver and brain were significantly increased in Cd-exposed groups. Low-level Cd exposure (1 mg/L) increased weight and length gains, as well as food intake, in the fish. Acetylcholinesterase activity decreased significantly in the Cd-exposed groups. Energy metabolism levels (as reflected by oxygen consumption, ammonia excretion rate, and swimming activity), as well as serum T3 and T4 levels, increased significantly in the fish exposed to 1 mg/L Cd. However, energy metabolism and serum T3/T4 levels decreased significantly in the 4-mg/L Cd group. Neuropeptide gene expression levels in brain were consistent with the observed changes in food intake. In the Cd-exposed groups, the expression levels of neuropeptide Y (NPY), apelin, and metallothionein (MT) increased significantly, while those of pro-opinmelanocortin (POMC), ghrelin, and corticotrophin-releasing factor (CRF) decreased significantly. Our data suggested that in fish, low doses of Cd might increase food intake, as well as weight and length gains, but high doses of Cd might have the opposite effect. These effects might be a result of neurohumoral regulation. Long-term exposure to low doses of Cd might cause weight gain and affect food intake.

Comparison measurement of unattached radon progeny concentration in three different environments.

Accurate measurement of unattached radon progeny is important for dose evaluation of radon exposure. For quality control of field surveys, a series of comparison measurements were carried out using three commercial unattached radon progeny monitors in real environments as well as in a radon chamber. The results show that the radon equilibrium equivalent concentrations (EECs) of different monitors agree very well, mostly within ±3.0% where there is no thoron progeny interference in the radon chamber. However, the unattached fraction of radon progeny is not so consistent, and the relative difference is 3.3% ~ 39.5% in different environments. The unattached fraction of radon progeny is affected by aerosol concentration. Anomalously high unattached fraction was found in the environment with extremely high humidity and low aerosol concentration. For accurate measurement of unattached radon progeny, specific attention should be paid to the collection efficiency of unattached radon progeny and the interference of attached radon progeny on a wire screen.

Sweet cherry fruit miRNAs and effect of high CO2 on the profile associated with ripening.

MAIN CONCLUSION: 157 known and 55 novel miRNAs were found in sweet cherry fruit. MiRNA target genes involved in fruit ripening and the differentially expressed miRNAs under CO2 treatment were identified. MicroRNAs (miRNAs) are short non-coding RNAs and play important functions in many biological processes, including fruit ripening and senescence. In the current study, the high-throughput sequencing and bioinformatics methods were implemented to decipher the miRNAs landscape in sweet cherry fruit. A total of 157 known miRNAs belonging to 50 families and 55 putative novel miRNAs were found. Target genes of the miRNAs were predicted and genes involved in fruit ripening were found, including F-box proteins and TFs such as SPL, TCP, NAC, MYB, ARF and AP2/ERF. And these target genes were further confirmed by degradome sequencing. A regulatory network model was constructed to uncover the miRNAs and their targets involved in fruit ripening and senescence. Importantly, elevated carbon dioxide can significantly postpone the ripening and senescence of sweet cherry fruit and the differentially expressed miRNAs exposed to CO2 were identified. These miRNAs included miR482j, miR6275, miR164, miR166, miR171, miR393, miR858, miR3627a, miR6284, miR6289 and miR7122b, and some of their functions were linked to fruit ripening. This study was the first report to profile miRNAs in sweet cherry fruit and it would provide more information for further study of miRNA roles in the ripening processes and their regulation mechanism underlying the effects of high carbon dioxide treatment on fruit ripening.

Effect of Bacillus cereus against cadmium induced hematological disturbances and immunosuppression in Carassius auratus gibelio.

Cadmium (Cd) is the most common heavy metal and is easily detected in aquatic environments worldwide. The genus Bacillus was one of dominant probiotics, which was commonly used in aquaculture. The present study was undertaken to explore the effects of Bacillus cereus (B. cereus) supplementation on hematological parameters and the immune response of Carassius auratus gibelio (C. gibelio) following Cd exposure. Fish were exposed to waterborne Cd (0, 1 and 2 mg/L) and/or treated with dietary B. cereus at 108 cfu/g for four weeks. The hematological disturbances observed after exposure of waterborne Cd included significant decreases in red blood cell (RBC) count, hemoglobin (Hb) concentration and hematocrit (HCT). While significant elevation (P < 0.05) of RBC count, HCT and Hb levels in the 1 and 2 mg/L Cd-B. cereus administration group at 4 weeks, compared with the Cd-only group. Among serum enzymatic activities, aspartate aminotransferase (AST) and alanine transaminase (ALT) activities by Cd exposure were significantly higher than controls, but this increase was effectively inhibited in Cd-B. cereus administration groups. In the Cd-B. cereus administration group, significant down-regulation of Hsp70, Hsp90, IL-1ß, IL-6, IL-10 and TNF-α in conjunction with the up-regulation of IgM and LZM in the spleen indicated that B. cereus alleviated the Cd-induced damage to the immune system to some degree. The results of this study suggested that B. cereus has the potential to countermeasure Cd-induced hematological disturbances and immunosuppression in C. gibelio.