High brightness edge-emitting laser diode with wavelength self-organization in ultra-broad emitting area.

We have proposed and experimentally demonstrated an efficient method for generating high power and brightness based on an ultra-broad area laser diode (UBALD). We have developed a single-emitter UBALD capable of self-organization multi-wavelength emissions for two stripe widths of 2 and 5 mm, respectively. The 2 mm UBALD delivers an output power of 55 W with a beam quality M2 of 1.3 × 25.3 and a brightness of 179 MW/(cm2·sr). The 5 mm UBALD produces an output power of 121 W with a beam quality M2 of 2.1 × 32.7 and a brightness of 192 MW/(cm2·sr). To the best of our knowledge, these results represent the highest output power and highest brightness ever achieved from a single edge-emitting LD emitter to date.

Molecular modification and biotechnological applications of microbial aspartic proteases.

The growing preference for incorporating microbial aspartic proteases in industries is due to their high catalytic function and high degree of substrate selectivity. These properties, however, are attributable to molecular alterations in their structure and a variety of other characteristics. Molecular tools, functional genomics, and genome editing technologies coupled with other biotechnological approaches have aided in improving the potential of industrially important microbial proteases by addressing some of their major limitations, such as: low catalytic efficiency, low conversion rates, low thermostability, and less enzyme yield. However, the native folding within their full domain is dependent on a surrounding structure which challenges their functionality in substrate conversion, mainly due to their mutual interactions in the context of complex systems. Hence, manipulating their structure and controlling their expression systems could potentially produce enzymes with high selectivity and catalytic functions. The proteins produced by microbial aspartic proteases are industrially capable and far-reaching in regulating certain harmful distinctive industrial processes and the benefits of being eco-friendly. This review provides: an update on current trends and gaps in microbial protease biotechnology, exploring the relevant recombinant strategies and molecular technologies widely used in expression platforms for engineering microbial aspartic proteases, as well as their potential industrial and biotechnological applications.

Pro-aromatic Dihydroquinazolinones - From Multigram Synthesis to Reagents for Gram-scale Metallaphotoredox Reactions.

Dihydroquinazolinone (DHQZ) has recently been harnessed as a ketone-derived pro-aromatic reagent extensively employed in (metalla)photoredox reactions as versatile group transfer agents. In this work, we outline a column chromatography-free protocol for the multigram-scale synthesis of pro-aromatic DHQZs as well as its use in a gram-scale nickel/photoredox dual-catalyzed cross-coupling in single-batch, photoflow, and simultaneous multiple smaller batches. While the single-batch approach leveraged moderate yields, a simple plug-flow photoreactor also exhibited amenable productivity (up to 45 % yield) despite the use of a heterogeneous base. Meanwhile, performing the metallaphotoredox-catalyzed reaction in multiple smaller batches in an improvised photoreactor facilitated high yields of up to 59 % and good reproducibility, implying a convenient alternative in the absence of photoflow setups.

Azetidines with All-Carbon Quaternary Centers: Merging Relay Catalysis with Strain Release Functionalization.

Given the importance and beneficial characteristics of decorated azetidines in medicinal chemistry, efficient strategies for their synthesis are highly sought after. Herein, we report a facile synthesis of the elusive all-carbon quaternary-center-bearing azetidines. By adopting a well-orchestrated polar-radical relay strategy, ring strain release of bench-stable benzoylated 1-azabicyclo[1.1.0]butane (ABB) can be harnessed for nickel-catalyzed Suzuki Csp2-Csp3 cross-coupling with commercially available boronic acids in broad scope (>50 examples), excellent functional group tolerance, and gram-scale utility. Preliminary mechanistic studies provided insights into the underlying mechanism, wherein the ring opening of ABB with a catalytic quantity of bromide accounts for the conversion of ABB into a redox-active azetidine, which subsequently engages in the cross-coupling reaction through a radical pathway. The synergistic bromide and nickel catalysis could intriguingly be derived from a single nickel source (NiBr2). Application of the method to modify natural products, biologically relevant molecules, and pharmaceuticals has been successfully achieved as well as the synthesis of melanocortin-1 receptor (MC-1R) agonist and vesicular acetylcholine transporter (VAChT) inhibitor analogues through bioisosteric replacements of piperidine with azetidine moieties, highlighting the potential of the method in drug optimization studies. Aside from the synthesis of azetidines, we demonstrate the ancillary utility of our nickel catalytic system toward the restricted Suzuki cross-coupling of tertiary alkyl bromides with aryl boronic acids to construct all-carbon quaternary centers.

1.9†µJ external-cavity dumped ultra-broad-area semiconductor nanosecond laser.

An external-cavity dumped nanosecond (ns) ultra-broad-area laser diode (UBALD) at around 966 nm with high pulse energy is demonstrated. A 1 mm UBALD is used to produce high output power and high pulse energy. A Pockels cell (PC) combines with two polarization beam splitters (PBSs) and is employed to cavity-dump a UBALD operating at 10 kHz repetition rate. At a pump current of 23 A, 11.4 ns pulses with a maximum pulse energy of ≈1.9 µJ and a maximum peak power of ≈166 W are achieved. The beam quality factor is measured to be M x 2=19.5 in the slow axis direction and M y 2=2.17 in the fast axis direction. Moreover, maximum average output power stability is confirmed, with a power fluctuation of less than 0.8% rms over 60 min. To the best of our knowledge, this is the first high-energy external-cavity dumped demonstration from an UBALD.

Compact 200 W level linearly polarized microsecond-pulse Nd:YAG oscillator with nearly diffraction-limited beam quality.

A compact 200 W level diode-side-pumped microsecond (µs) pulse linearly polarized rod Nd:YAG laser oscillator was demonstrated with nearly diffraction-limited beam quality. The oscillator was based on a thermally near-unstable cavity design with two concave lenses in the cavity to enlarge the volume of the fundamental mode, leading to improvement of the laser efficiency and beam quality. Consequently, a record-high average power of 222 W was obtained at a repetition rate of 400 Hz with a 180 µs pulse width, corresponding to an optical-to-optical (o-o) conversion efficiency of 37%. The average beam quality factor was measured to be M2=1.32, resulting in a brightness value as high as of 11.25GW/sr⋅cm2. To the best of our knowledge, this represented the highest average power, the highest o-o efficiency, and the highest brightness for a µs pulse 1064 nm rod Nd:YAG laser oscillator.

Dual-CRISPR/Cas12a-Assisted RT-RAA for Ultrasensitive SARS-CoV-2 Detection on Automated Centrifugal Microfluidics.

The clustered regularly interspaced short palindromic repeats (CRISPR)-based nucleic acid detection can be combined with recombinase-aided amplification (RAA) to enable rapid, accurate, and early detection of SARS-CoV-2. Current CRISPR-based approaches to detecting viral nucleic acid typically require immense manual operations to transfer RPA amplicons for CRISPR detection or suffer from compromised sensitivity by mixing the competing RPA amplification and CRISPR detection. Here, we develop dual-CRISPR/Cas12a-assisted RT-RAA assay and a ″sample-to-answer″ centrifugal microfluidic platform that can automatically detect 1 copy/µL of the SARS-CoV-2 within 30 min. This chip separates the amplification (RAA) from detection (CRISPR), such that sensitivity is maximized and the time consumption is decreased by a factor of 3. For the 26 positive and 8 negative clinical SARS-CoV-2 samples, this automated centrifugal microfluidics achieved 100% accuracy compared to the gold-standard RT-PCR technique. This point-of-care test, with the advantages of being one-step, automated, rapid, and sensitive, will have a significant potential for clinical diagnosis and disease prevention.

Nanosecond pulsed single longitudinal mode diamond Raman laser in the 1.6†µm spectral region.

We demonstrate the first nanosecond pulsed single longitudinal mode (SLM) intracavity-pumped diamond Raman laser, to the best of our knowledge. The eye-safe coherent source at 1634 nm, which was converted from the actively Q-switched 1342 nm Nd:YVO4 laser, yielded 4.35 W of multimode average output power with a pulse duration of 6 ns and peak power of 29 kW. By exploiting the spatial hole burning free gain mechanism in the Raman media, stable SLM operation was observed at low output power (0.46 W) for the free-running case. Furthermore, by incorporating an etalon in the fundamental standing-wave cavity, the spectral linewidth of the fundamental field was suppressed substantially below the diamond Raman gain linewidth and slightly less than the free spectral range of the mm-scale Raman resonator. Thereby, a much higher SLM output power of 1.63 W was obtained with a pulse duration of ∼9 ns and a spectral linewidth of ∼77 MHz.

Microfluidic preparation of a novel phoxim nanoemulsion pesticide against Spodoptera litura.

With continuous development of pesticide dosage forms, emulsifiable concentrates using large amounts of organic solvents are gradually obsoleted. Nanoemulsions with high water content have been developed and the preparation processes also evolved, but these processes still exist some problems, such as poor controllability and high energy consumption. Microfluidic is a controllable nanoemulsion preparation system which mainly applied to pharmaceutical synthesis. In this study, the pesticide phoxim nanoemulsion was prepared by microfluidic technology. The optimized formulation of phoxim nanoemulsion was composed of Tween 80 and pesticide emulsifier 500 as surfactant, hexyl acetate as oil, and n-propanol as co-surfactant. Moreover, when the flow rates of water and oil in the microfluidic system were adjusted to 5 µL/min and 20 µL/min, phoxim nanoemulsion was obtained with a cloud point/boiling point of 109 °C, a particle size of 21.5 ± 0.8 nm and a potential value of - 18.7 ± 0.6 mV. Furthermore, the nanoemulsion had a rapid release effect in vitro which could be fitted by the Ritger-Peppas model. The feeding toxicity of the phoxim nanoemulsion was higher than that of commercial formulation while the contact killing effect was higher than that of the active ingredient. Therefore, pesticide dosage was reduced and the insecticidal effect was enhanced by using phoxim nanoemulsions. These results also confirm the potential of microfluidics as a green process to produce pesticide nanoemulsions.

1.53 W all-solid-state nanosecond pulsed mid-infrared laser at 6.45 µm.

A compact and robust all-solid-state mid-infrared (MIR) laser at 6.45 µm with high average output power and near-Gaussian beam quality is demonstrated. A maximum output power of 1.53 W with a pulse width of approximately 42 ns at 10 kHz is achieved using a ZnGeP2 (ZGP) optical parametric oscillator (OPO). This is the highest average power at 6.45 µm of any all-solid-state laser to the best of our knowledge. The average beam quality factor is measured to be M2 = 1.19. Moreover, high output power stability is confirmed, with a power fluctuation of less than 1.35% rms over 2 h, and the laser can run efficiently for more than 500 h in total. Using this 6.45 µm pulse as a radiation source, ablation of animal brain tissue is tested. Furthermore, the collateral damage effect is theoretically analyzed for the first time, to the best of our knowledge, and the results indicate that this MIR laser has excellent ablation ability, making it a potential replacement for free electron lasers.

Automated Centrifugal Microfluidic Chip Integrating Pretreatment and Molecular Diagnosis for Hepatitis B Virus Genotyping from Whole Blood.

Point-of-care (POC) testing for nucleic acid that combines pretreatment and molecular diagnosis is crucial in analyzing complex samples such as those encountered in clinical diagnosis. Herein, we developed a centrifugal microfluidic platform, which can achieve a series of functions including separating serum and adsorbing, washing, eluting, and detecting DNA. We combined multiple signal enhancement systems including recombinase polymerase amplification (RPA), T7 transcription technology, and clustered regularly interspaced short palindromic repeat (CRISPR) technology to yield an ultrabright signal, which can avoid false-negative results. As an application, hepatitis B virus (HBV), a virus that causes global public health problems, was successfully detected and genotyped from whole blood on the automated centrifugal microfluidic platform. Compared to the traditional diagnosis process, the POC platform largely decreased the consumption of time from 3 to 1 h and the consumption of professional labor from three persons to only one. The automated centrifugal microfluidic platform integrated pretreatment and molecular diagnosis will play an essential role in clinical detection.

Desulfurative Ni-Catalyzed Reductive Cross-Coupling of Benzyl Mercaptans/Mercaptoacetates with Aryl Halides.

The C-S activation and sulfur removal from native thiols is challenging, which limits their application as feedstock materials in organic synthesis despite their natural abundance. Herein, we introduce a per-/polyfluoroaryl moiety, which serves as a redox-active scaffold, into sp3-hybridized thiols to activate the C-S bond. Using a Ni catalyst with MgBr2 as an additive, the S group can be removed to yield an aliphatic radical that can react with an aryl halide in a reductive cross-coupling.

Aromatization as an Impetus to Harness Ketones for Metallaphotoredox-Catalyzed Benzoylation/Benzylation of (Hetero)arenes.

Herein we report ketones as feedstock materials in radical cross-coupling reactions under Ni/photoredox dual catalysis. In this approach, simple condensation first converts ketones into prearomatic intermediates that then act as activated radical sources for cross-coupling with aryl halides. Our strategy enables the direct benzylation/benzoylation of (hetero)arenes under mild reaction conditions with high functional group tolerance.

2.55 W continuous-wave 378 nm laser by intracavity frequency doubling of a diode-pumped Alexandrite laser.

A high-power continuous-wave (CW) ultraviolet (UV) laser at 378 nm from an intracavity frequency-doubled Alexandrite laser has been demonstrated with 638 nm fiber-coupled laser diodes as the pump source. A maximum output power of 2.55 W was obtained, which is the highest power for CW frequency-doubled Alexandrite lasers, to the best of our knowledge, corresponding to the optical-to-optical conversion efficiency of 7.9% from 638 nm pump laser to 378 nm UV laser. The beam quality factors M2 were measured to be 2.19 and 2.47 in x and y directions at UV output power of 1 W, respectively.

[Dynamic characteristics of brain networks in patients with irritable bowel syndrome based on functional magnetic resonance imaging].

The disorder of brain-gut interaction is an important cause of irritable bowel syndrome (IBS), but the dynamic characteristics of the brain remain unclear. Since there are many shortcomings for evaluating brain dynamic nature in the previous studies, we proposed a new method based on slope calculation by point-by-point analysis of the data from functional magnetic resonance imaging, and detected the abnormalities of brain dynamic changes in IBS patients. The results showed that compared with healthy subjects, there were dynamic changes in the brain for the IBS patients. After correction by false discovery rate (FDR), significant abnormalities were only found in two functional connections of the right posterior cingulate gyrus linked to left middle frontal gyrus, and the right posterior cingulate gyrus linked to left pallidus. The above results of the brain dynamic analysis were totally different from those of the brain static analysis of IBS patients. Our findings provide novel complementary information for illustrating the central nervous mechanism of IBS and may offer a new direction to explore central target for patients with IBS.

[ARTICLE WITHDRAWN] Semiconducting Polymer Dot-Based Ratiometric Fluorescence Nanoprobe for DNA Detection.

THIS ARTICLE WAS WITHDRAWN BY THE PUBLISHER IN MAY 2021

Excellent performance of a cryogenic Nd:YAlO3 laser with low wavefront distortion based on zero thermal expansion.

High-power solid-state lasers with good beam quality are attracting great attention on account of their important applications in industry and military. However, the thermal effects generated in the laser host materials seriously limit power scaling and degrade the beam quality. Thermal lensing and thermally induced wavefront deformation are the main causes of the beam quality deterioration. Here we investigate the performance of a zero thermal expansion (ZTE) solid-state laser gain material. In a proof-of-principle experiment, an ${a}$-cut rod ${\rm Nd}\!:\!{{\rm YAlO}_3}$ (Nd:YAP) perovskite crystal is chosen to be the gain medium for ZTE around 180 K. The laser performance spanning the temperature range from 80 to 290 K is studied. The maximum output power and minimum threshold pump power were obtained at a temperature of 180 K. Moreover, the measured thermal focal power and peak-to-valley value of the wavefront distortion also reach a minimum at this temperature, an additional benefit from the crystal's ZTE coefficient. We envisage that these results will open a new route towards the development of high-power and high-beam-quality lasers through the use of ZTE gain materials.

Tunable deep ultraviolet laser based near ambient pressure photoemission electron microscope for surface imaging in the millibar regime.

A newly developed instrument comprising a near ambient pressure (NAP) photoemission electron microscope (PEEM) and a tunable deep ultraviolet (DUV) laser source is described. This NAP-PEEM instrument enables dynamic imaging of solid surfaces in gases at pressures up to 1 mbar. A diode laser (976 nm) can illuminate a sample from the backside for in situ heating in gases up to 1200 K in minutes. The DUV laser with a tunable wavelength between 175 nm and 210 nm is perpendicularly incident onto the sample surface for PEEM imaging of a wide spectrum of solids with different surface work functions. Using this setup, we have first demonstrated spatiotemporal oscillation patterns of CO oxidation reaction on Pt(110) from high vacuum to NAPs and gas-induced restructuring of metal nanostructures in millibar gases. The new facility promises important applications in heterogeneous catalysis, electrochemical devices, and other surface processes under nearly working conditions.

22.9 W CW single-frequency laser at 671 nm by frequency doubling of Nd:YVO4 laser.

A stable, 22.9 W, 671 nm single-frequency laser using a type II noncritically phase-matched external-cavity frequency doubling is demonstrated. The output power of the fundamental laser is 32.1 W; the corresponding conversion efficiency of frequency doubling from 1342 to 671 nm is calculated to be 71.3%. The M2 factors are measured to be 1.10 and 1.08 in the x and y directions, respectively. To the best of our knowledge, 22.9 W is the highest power obtained for a 671 nm single-frequency laser.

30 W single-frequency continuous-wave master oscillator power amplifier laser at 1342 nm.

We present a power-scalable high-power single-frequency continuous-wave 1342 nm master oscillator power amplifier (MOPA) system that consists of a polarized single-frequency 1342 nm LD seed laser, a Raman fiber preamplifier, and a three-stage ${\rm Nd}:{{\rm YVO}_4}$Nd:YVO4 power amplifier. The single-frequency output power of 30 W at 1342 nm is achieved with the beam quality factors ${{\rm M}^{2\:}} = {1}.{26}$M2=1.26, and the power stability for 1 h is better than ${\pm }\;{0}.{5}\% $±0.5%.