Massively parallel FMCW lidar with cm range resolution using an electro-optic frequency comb.

Frequency-modulated continuous wave (FMCW) light detection and ranging (lidar) is a promising solution for three-dimensional (3D) imaging and autonomous driving. This technique maps range and velocity measurement to frequency counting via coherent detection. Compared with single-channel FMCW lidar, multi-channel FMCW lidar can greatly improve the measurement rate. A chip-scale soliton micro-comb is currently used in FMCW lidar to enable multi-channel parallel ranging and significantly increase the measurement rate. However, its range resolution is limited due to the soliton comb having only a few-GHz frequency sweep bandwidth. To overcome this limitation, we propose using a cascaded modulator electro-optic (EO) frequency comb for massively parallel FMCW lidar. We demonstrate a 31-channel FMCW lidar with a bulk EO frequency comb and a 19-channel FMCW lidar using an integrated thin-film lithium niobate (TFLN) EO frequency comb. Both systems have a sweep bandwidth of up to 15 GHz for each channel, corresponding to a 1-cm range resolution. We also analyze the limiting factors of the sweep bandwidth in 3D imaging and perform 3D imaging for a specific target. The measurement rate achieved is over 12 megapixels per second, which verifies its feasibility for massively parallel ranging. Our approach has the potential to greatly benefit 3D imaging in fields where high range resolution is required, such as in criminal investigation and precision machining.

Effect of different irrigation levels on quality parameters of 'Honeycrisp' apples.

BACKGROUND: Water shortage is the main factor affecting agricultural production in the vast arid and semi-arid areas of northern China. Using proper irrigation methods can optimize the efficiency of water use and improve the quality of agricultural products. This study investigated the effect of different irrigation levels on the quality of 'Honeycrisp' apples grown in the Loess Plateau of northern China. RESULTS: Different irrigation levels were applied to the 'Honeycrisp' apple trees via root irrigation using ceramic emitters that provide saturation levels of 75-90% Î¸f (S1, where θf is the field capacity), 60-75% Î¸f (S2), 45-50% Î¸f (S3) and no irrigation treatment (CK). Compared to the apples from the CK group, the water content, transverse diameter, individual fruit weight and titratable acid content of S1 and S2 group apples increased significantly. However, their hardness, soluble solids and total sugar content decreased significantly. The phenolic acid content of apples also changed with the irrigation levels. The chlorogenic acid content of apples increased with increased irrigation volume, while the hyperoside, protocatechuic acid and caffeic acid content decreased. Total phenolic and flavonoid contents of fruits were the highest in S2 group apples. They also had the strongest ABTS and DPPH free radical scavenging capacities. CONCLUSION: The volume of irrigation applied through ceramic emitters significantly impacted the quality of 'Honeycrisp' apples grown in loess areas. Considering water conservation and improving fruit quality, the most suitable ceramic root irrigation level was observed to be 60-75% Î¸f (S2). © 2021 Society of Chemical Industry.

Urban development pattern's influence on extreme rainfall occurrences.

Growing urban population and the distinct strategies to accommodate them lead to diverse urban development patterns worldwide. While local evidence suggests the presence of urban signatures in rainfall anomalies, there is limited understanding of how rainfall responds to divergent urban development patterns worldwide. Here we unveil a divergence in the exposure to extreme rainfall for 1790 inland cities globally, attributable to their respective urban development patterns. Cities that experience compact development tend to witness larger increases in extreme rainfall frequency over downtown than their rural surroundings, while the anomalies in extreme rainfall frequency diminish for cities with dispersed development. Convection-permitting simulations further suggest compact urban footprints lead to more pronounced urban-rural thermal contrasts and aerodynamic disturbances. This is directly responsible for the divergent rainfall responses to urban development patterns. Our analyses offer significant insights pertaining to the priorities and potential of city-level efforts to mitigate the emerging climate-related hazards, particularly for countries experiencing rapid urbanization.

Novel Fluorescent Nanocellulose Hydrogel Based on Nanocellulose and Carbon Dots for Detection and Removal of Heavy Metal Ions in Water.

Water is an important raw material in the food production process. Maintaining the quality and safety of water is very important in the food field. In this study, a simple novel fluorescent nanocellulose hydrogel (FNH) was prepared for the detection and removal of heavy metals (Fe3+ and Pb2+) in aqueous solutions based on carbon dots (CDs). The CDs were grafted onto the carboxylated nanocellulose (CNC) by the EDC/NHS coupling method, and then the nanocellulose (NC), CNC, and FNH were characterized by FTIR analysis. The effect of adsorption environment on FNH adsorption capacity was also investigated. After carboxylation and grafting of CDs, the adsorption capacity of nanocellulose to Fe3+ and Pb2+ was greatly improved, and it was also allowed to make fast visual responses to Fe3+ as an optical sensor to determine the concentration of Fe3+ through the visual signal. Static adsorption experiment demonstrated that the removal rate of Fe3+ and Pb2+ by FNH exceeded 69.4% and 98.2%, and the adsorption capacity amount reached 98.3 mg/g and 442.0 mg/g. At the same time, due to the fluorescence quenching effect of Fe3+, FNH could also be used for the detection of Fe3+ concentration in aqueous solution, and the limit of detection (LOD) could reach 62.5 mg/L.

Nanocellulose Prepared from Buckwheat Bran: Physicochemical Characterization, Cytotoxicity Evaluation, and Inhibition Effect on Fat Digestion and Absorption.

Cellulose nanocrystal (CNC) is a sustainable biomaterial that has been used in many aspects of the food industry, but its effect on fat digestion and absorption is still underexplored. In this study, three CNCs were prepared from buckwheat bran. Their physicochemical properties were characterized, based on which the acetic acid-hydrolyzed CNC (ACCNC) with high absorption capacity was selected for the cytotoxicity evaluation and as a possible inhibitor for fat digestion and absorption in vitro and in vivo. ACCNC was proved to be nontoxic in the MTT assay and animal feeding tests. Especially, with the addition of ACCNC, the hydrolysis of fat was significantly reduced during the simulated digestion in vitro. In vivo testing also confirmed that ACCNC intake significantly reduced the elevated triglyceride, body weight, and fat accumulation levels. This study highlights the potential role of ACCNC prepared from buckwheat bran as an inhibitor for fat digestion and absorption.

Ferulic acid attenuates high-fat diet-induced hypercholesterolemia by activating classic bile acid synthesis pathway.

Ferulic acid (FA), a natural phenolic phytochemical abundantly present in whole grains, displays promising therapeutic effects on hypercholesterolemia while its underlying mechanism not fully elucidated. This study aimed to investigate the cholesterol-lowering effect of FA in high-fat diet (HFD)-fed mice and its potential molecular mechanism. FA supplementation alleviated HFD-induced hypercholesterolemia (-13.2%, p < 0.05), along with increased excretion of bile acids (BAs) in feces (37.0%, p < 0.05). Mechanism studies showed that FA activated the expression of cholesterol 7α hydroxylase (CYP7A1), a rate-limiting enzyme in BA biosynthesis in the liver, which increased the BAs biosynthesis from cholesterol. Surprisingly, increased excretion of BAs in feces is a consequence, not a cause, of CYP7A1 activation. Furthermore, enterohepatic farnesoid X receptor (FXR) signaling is not involved in the activation of hepatic CYP7A1 by FA. In conclusion, FA activates CYP7A1 through non-FXR signaling, which on the one hand effectively prevents hypercholesterolemia, and on the other hand leads to secondary BAs elevation in plasma. The latter may be the key to the anti-obesity and hypoglycemic effects of FA.

Development of Fluorescence Polarization Immunoassay for Imidacloprid in Environmental and Agricultural Samples.

A fluorescence polarization immunoassay (FPIA) for the determination of imidacloprid (IMI) was developed with advantages of simple operation and short assay time. The haptens of IMI, acetamiprid (ACE), and thiamethoxam (THI) were conjugated with fluorescein isothiocyanate ethylenediamine (EDF) and 4'-Aminomethyl fluorescein (AMF), respectively, to prepare six fluorescence tracers. The conjugation of IMI hapten and EDF (IMI-EDF) was selected to develop the FPIA due to the largest fluorescent polarization value increase in the presence of anti-IMI monoclonal antibody. Under the optimum condition, the limit of detection, 50% inhibition concentration and detection range of the FPIA were 1.7, 4.8, and 1.7-16.3 µg/L, respectively. The cross-reactivities (CRs) with the analogs of IMI were negligible except for imidaclothiz with CR of 79.13%. The average recovery of spiked paddy water, corn and cucumber samples were 82.4-118.5% with the RSDs of 7.0-15.9%, which indicated the FPIA had good accuracy. Thus, the developed FPIA was a potential tool for the rapid and accurate determination of IMI in agricultural and environmental samples.

Evaluation studies on effects of quercetin with different concentrations on the physicochemical properties and in vitro digestibility of Tartary buckwheat starch.

The effects of polyphenols on the physicochemical properties and in vitro digestibility of Tartary buckwheat starch (TBS) remain scarce. In this study, the rheological, thermal properties, and in vitro digestibility of pregelatinized TBS (pre-TBS) with quercetin complexation at various concentrations were characterized. It was found that quercetin complexation increased the shearing resistance and viscosity of pre-TBS. Both SEM and TGA results revealed a more compact and stable structure of starch-quercetin complex in comparison to pre-TBS. The non-inclusive complex with higher crystallinity was formed through hydrogen bonds, which showed by XRD and FT-IR results. Additionally, complexes exhibited the lower digestion rate and digestion velocity constant, and the resistant starch content of complex (with 10% quercetin addition) was the highest. Therefore, quercetin complexation could improve the thermal and rheological properties, and decrease in vitro digestibility of pre-TBS, which could provide a theoretical basis for functional food development.

Population dynamics modify urban residents' exposure to extreme temperatures across the United States.

Exposure to extreme temperatures is one primary cause of weather-related human mortality and morbidity. Global climate change raises the concern of public health under future extreme events, yet spatiotemporal population dynamics have been long overlooked in health risk assessments. Here, we show that the diurnal intra-urban movement alters residents' exposure to extreme temperatures during cold and heat waves. To do so, we incorporate weather simulations with commute-adjusted population profiles over 16 major U.S. metropolitan areas. Urban residents' exposure to heat waves is intensified by 1.9° ± 0.7°C (mean ± SD among cities), and their exposure to cold waves is attenuated by 0.6° ± 0.8°C. The higher than expected exposure to heat waves significantly correlates with the spatial temperature variability and requires serious attention. The essential role of population dynamics should be emphasized in temperature-related climate adaptation strategies for effective and successful interventions.

Development of immunochromatographic assays for the detection of imidacloprid in soil chemical barrier.

A soil chemical barrier is the most important and common way to control termites; fast and on-site detection methods are significant tools to verify pesticide content meeting the standard requirements. In this study, conventional and enhanced immunochromatographic assays (ICAs) containing two test lines (TLs) were developed to semi-quantitatively detect imidacloprid in soil chemical barrier, and detection results were quantified by a smart phone. According to the results, the disappearance concentrations of first TL (TL-1) and second TL (TL-2) in an enhanced ICA and conventional ICA were 5 and 20 ng/mL and 20 and 80 ng/mL with the naked eye. The sensitivity of TL-2 was four times that of TL-1 in both ICAs, consistent with the maximum and minimum concentration differences for imidacloprid in Jiangsu province's "the technical regulation of assay and evaluation on chemical soil barrier of termite prevention treatment in buildings". The results of TLs can be used to judge whether the amount of imidacloprid in soil chemical barrier meets the standard. Enhanced and conventional ICAs were available for further quantitative testing with a smart phone, and the limit of detection (LOD) was 0.74 and 3.17 ng/mL, respectively. Moreover, some soil chemical barrier samples from several areas in Wuxi, Jiangsu province, were used to test by ICAs and high-performance liquid chromatography (HPLC), and the results of ICAs correlated well with HPLC.

Development of immunoassays for detecting oxyfluorfen residue in agricultural and environmental samples.

An enzyme-linked immunosorbent assay (ELISA) and chemiluminescent immunoassays (CLEIA) were developed to detect oxyfluorfen in agricultural and environmental samples. The hapten of oxyfluorfen was synthesized and conjugated with bovine serum albumin (BSA) and ovalbumin (OVA) to produce immunogen and coating antigen. One cell line (1A7D6F5) that stably secretes anti-oxyfluorfen monoclonal antibody (mAb) is obtained by cell fusion. Under optimal conditions, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC20) of ELISA are 0.065 mg L-1 and 0.0048 mg L-1, while those of CLEIA are 0.021 mg L-1 and 0.0016 mg L-1, respectively. The immunoassays show no obvious cross-reactivities with the analogues of oxyfluorfen except for benzofluorfen and bifenox. The recoveries of oxyfluorfen in the spiked samples of soil, grape, peach, apple and pear are in the range of 74.1-107.2% with a RSD of 2.7-9.7% for ELISA, and 77.2-106.4% with a RSD of 2.4-7.9% for CLEIA. The results of immunoassays for the authentic samples are significantly correlated with those detected by gas chromatography (GC).

Direct competitive fluoroimmunoassays for detection of imidaclothiz in environmental and agricultural samples using quantum dots and europium as labels.

A direct quantum dots-based fluoroimmunoassay (QDFIA) and a time-resolved fluoroimmunoassay (TRFIA) for imidaclothiz (IMI) were developed by using the quantum dots (QDs)-labeled antibody and the europium (Eu3+)-labeled antibody, respectively. After optimization, the half-maximal inhibition concentration (IC50) and the limit of detection (LOD, IC10) are 20.41 and 0.52µgL-1 for the QDFIA, while 6.91 and 0.018µgL-1 for the TRFIA, respectively. The cross-reactivities (CRs) with the analogues are negligible except for imidacloprid with CRs of 29.0% for the QDFIA and 26.6% for the TRFIA. The spiked recoveries of IMI in paddy water, soil, pear, tomato, rice, apple, cabbage and cucumber are 72.7-117.6% with a standard deviation (RSD) of 2.4-13.5% for the QDFIA, and 81.3-117.7% with a RSD of 1.6-7.5% for TRFIA. The detection results of the analyses for the real paddy water and pear samples are markedly correlated with these of high-performance liquid chromatography (HPLC).

Development of a phage chemiluminescent enzyme immunoassay with high sensitivity for the determination of imidaclothiz in agricultural and environmental samples.

In this study, we isolated six phage-displayed peptides by biopanning phage-displayed peptide libraries on an immobilized anti-imidaclothiz monoclonal antibody. After analyzing the relative sensitivity of the individual phage-displayed peptides, we subsequently developed and optimized both a phage enzyme immunoassay (P-ELISA) and a phage chemiluminescent enzyme immunoassay (P-CLEIA) to improve the sensitivity and linear range of imidaclothiz assays. The P-CLEIA (50% inhibition concentration (IC50) of 0.86ngmL-1, linear range of 0.13-5.84ngmL-1) was more sensitive and had a wider linear range compared to the P-ELISA (IC50 of 1.45ngmL-1, linear range of 0.55-3.82ngmL-1). Besides, the sensitivities of the P-ELISA and P-CLEIA were increased by >4-fold and 8-fold, respectively as compared to homologous immunoassays developed using the same monoclonal antibody. Neither method had significant cross-reactivity with the analogues of imidaclothiz except for imidacloprid. Recoveries of the P-ELISA and P-CLEIA for imidaclothiz in paddy water, soil, cabbage, rice, apple, pakchoi, pear and tomato samples were 72.3-101.3% and 73.9-102.6%, respectively. The P-ELISA and P-CLEIA detected imidaclothiz in the authentic samples, and showed good correlation with results obtained from high-performance liquid chromatography (HPLC).