Vibration to Vibration: Product Energy Distribution of F + HD Crossed Molecular Beam Experiments.

We investigated the F + HD(v = 1, j = 0) → HF + D reaction using the crossed molecular beam technique combined with the D atom Rydberg tagging time-of-flight spectroscopy. By detecting the products at various scattering angles for different collision energies in the range of 0.8-1.2 kcal/mol, we observed the forward-scattering products of HF(v' = 4) and determined the threshold energy for the opening of this reaction channel. Similar experiments were conducted for the F + HD(v = 0, j = 0) → HF + D reaction within the range of 1.1-1.6 kcal/mol, where forward-scattering products of HF(v' = 3) were observed, and the threshold energy for this reaction channel was determined as well. Furthermore, we measured the differential cross-sections for the F + HD → HF + D reaction in both the vibrational ground state and the excited state of HD and analyzed the vibrational quantum-state distribution of the HF products. It was found that the population of vibrational quantum states of the HF products increases synchronously with the excitation of the reactant HD vibrationally.

Time-Resolved Ultraviolet Photodissociation Mass Spectrometry Probes the Mutation-Induced Alterations in Protein Stability and Unfolding Dynamics.

How mutations impact protein stability and structure dynamics is crucial for understanding the pathological process and rational drug design. Herein, we establish a time-resolved native mass spectrometry (TR-nMS) platform via a rapid-mixing capillary apparatus for monitoring the acid-initiated protein unfolding process. The molecular details in protein structure unfolding are further profiled by a 193 nm ultraviolet photodissociation (UVPD) analysis of the structure-informative photofragments. Compared with the wild-type dihydrofolate reductase (WT-DHFR), the M42T/H114R mutant (MT-DHFR) exhibits a significant stability decrease in TR-nMS characterization. UVPD comparisons of the unfolding intermediates and original DHFR forms indicate the special stabilization effect of cofactor NADPH on DHFR structure, and the M42T/H114R mutations lead to a significant decrease in NADPH-DHFR interactions, thus promoting the structure unfolding. Our study paves the way for probing the mutation-induced subtle changes in the stability and structure dynamics of drug targets.

Polymeric Metal Halides with Bright Luminescence and Versatile Processability.

Most of current metal halide materials, including all inorganic and organic-inorganic hybrids, are crystalline materials with poor workability and plasticity that limit their application scope. Here, we develop a novel class of materials termed polymeric metal halides (PMHs) through introducing polycations into antimony-based metal halide materials as A-site cations. A series of PMHs with orange-yellow broadband emission and large Stokes shift originating from inorganic self-trapped excitons are successfully prepared, which meanwhile exhibit the excellent processability and formability of polymers. The versatility of these PMHs is manifested as the broad choices of polycations, the ready extension to manganese- and copper-based halides, and the tolerance to molar ratios between polycations and metal halides in the formation of PMHs. The merger of polymer chemistry and inorganic chemistry thus provides a novel generic platform for the development of metal halide functional materials.

Factors predicting indistinct plane of surgical capsule in patients underwent HoLEP procedures.

PURPOSE: To evaluate factors that effectively predict indistinct plane (IP) in patients who underwent holmium laser enucleation of the prostate (HoLEP). METHODS: Data of 208 consecutive patients from our HoLEP database were reviewed and analyzed. IP was defined in 107 cases, as the plane could be identified only depending on endoscopic beak dissection rather than laser dissection in the initial stage of HoLEP, whereas the control group consisted of 101 cases. Variables including age, body mass index, prostatic volume (PV), intravesical prostatic protrusion, prostate-specific antigen, prostate-specific antigen density, bladder stones, urinary tract infection, microscopic hematuria, prior biopsy (PB), diabetes, hypertension, history of acute urinary retention, 5-alpha reductase inhibitor treatment, catheter dependency, residual urine, region, smoking, and alcohol consumption were compared between the two groups. The risk factors for predicting the presence of IP were determined using a multivariable binary logistic regression model using a forward selection approach with a focus on improvement in the area under the receiver operating characteristic curve (AUC). RESULTS: The incidence of IP was 51.4% (107/208). PV (OR = 0.977, p < 0.001) and PB (OR = 0.297, p = 0.028) were identified as the independent predictors of capsule plane status. PV with a cutoff of 54 ml had the best predictive effectiveness for IP based on AUC (0.727; 95% CI 0.659-0.795). The specificity and sensitivity of this cutoff were 82.2% and 53.3%, respectively. CONCLUSION: PV is the most reliable factor to predict IP during HoLEP procedures. There is a high possibility of IP in patients with a PV less than 54 ml.

Molecular Structure Characterization of Micro/Nanoplastics by 193 nm Ultraviolet Photodissociation Mass Spectrometry.

The degradation of macroplastics results in micro/nanoplastics (MNPs) in the natural environment, inducing high health risks worldwide. It remains challenging to characterize the accurate molecular structures of MNPs. Herein, we integrate 193 nm ultraviolet photodissociation (UVPD) with mass spectrometry to interrogate the molecular structures of poly(ethylene glycol) terephthalate and polyamide (PA) MNPs. The backbones of the MNP polymer can be efficiently dissociated by UVPD, producing rich types of fragment ions. Compared to high-energy collision dissociation (HCD), the structural informative fragment ions and corresponding sequence coverages obtained by UVPD were all improved 2.3 times on average, resulting in almost complete sequence coverage and precise structural interrogation of MNPs. We successfully determine the backbone connectivity differences of MNP analogues PA6, PA66, and PA610 by improving the average sequence coverage from 26.8% by HCD to 89.4% by UVPD. Our results highlight the potential of UVPD in characterizing and discriminating backbone connectivity and chain end structures of different types of MNPs.

V.I.P. Score: A Comprehensive Grading System to Predict Difficulty of HoLEP Procedure for Small-to-Moderate Sized Prostate (<120 mL).

OBJECTIVE: To develop a comprehensive scoring system in addition to the conventionally used prostatic volume (PV), for predicting the difficulty of holmium laser enucleation of the prostate (HoLEP) that may arise with small-to-moderate sized prostate. METHODS: We retrospectively reviewed 151 consecutive patients who underwent HoLEP and had a PV less than 120 mL. Based on previous literature, a difficult procedure was defined as a prolonged operative time (OT>90 minute) in 88 cases, while the control group (OT≤90 minute) consisted of 63 patients. The clinical data, including age, body mass index, PV, intravesical prostatic protrusion (IPP), prostate specific antigen (PSA), prostate specific antigen density, urinary tract infection, microscopic hematuria, prior biopsy, diabetes mellitus, hypertension, history of acute urinary retention, catheter dependency and use of antiplatelet / anticoagulation drugs or 5-alpha reductase inhibitor were compared between the 2 groups. RESULTS: Univariate analysis revealed significant differences between the 2 groups. Multivariate analysis identified 3 main independent predictors for difficulty, including volume (V) (60-90 mL OR = 9.812, P < .001) (≥90 mL OR = 18.173, P = .01), IPP (I) (OR = 3.157, P = .018), and PSA (P) (≥4 ng/ml OR = 16.738, P < .001). Therefore, a V.I.P. score was developed based on the regression model and ranged from 0 to 7 points. The area under the curve showed preferable predictive ability of the V.I.P. score compared to PV (0.906 vs 0.869). CONCLUSION: We developed a V.I.P. score that can accurately predict the difficulty of the HoLEP procedure for PV less than 120 mL in order to optimize clinical outcomes.

Endoscopic Laser Dissection Combined With Laparoscopic Pneumovesical Repair of Vesicovaginal Fistula: A Novel Technique and Case Report.

INTRODUCTION: We present a novel technique that combined endoscopic laser dissection and a transvesical laparoscopic approach for VVF repair in a transmasculine patient who received vaginal colpectomy. A literature review of VVF repair was also conducted. TECHNICAL CONSIDERATIONS: Surgical repair of VVF has been described extensively in the literature. Transvaginal and transabdominal laparoscopic approaches are currently the most common techniques for VVF management. However, for transmasculine patients, neither of these methods is ideal due to either a previous history of vaginal colpectomy or the position of the fistula. This case report demonstrates the feasibility of applying a combined endoscopic laser dissection and transvesical laparoscopic approach for VVF repair. CONCLUSION: The patient had an uneventful recovery, and the VVF healed over time. The advantages of this technique include a precise incision and dissection of the fistula orifice, clear exposure of the anatomic plane between the bladder and vaginal wall, and minimal injury to normal tissue. More cases are needed to demonstrate the effectiveness and complication rate of this technique in the future.

Stereodynamical control of the H + HD → H2 + D reaction through HD reagent alignment.

Prealigning nonpolar reacting molecules leads to large stereodynamical effects because of their weak steering interaction en route to the reaction barrier. However, experimental limitations in preparing aligned molecules efficiently have hindered the investigation of steric effects in bimolecular reactions involving hydrogen. Here, we report a high-resolution crossed-beam study of the reaction H + HD(v = 1, j = 2) → H2(v', j') + D at collision energies of 0.50, 1.20, and 2.07 electron volts in which the vibrationally excited hydrogen deuteride (HD) molecules were prepared in two collision configurations, with their bond preferentially aligned parallel and perpendicular to the relative velocity of collision partners. Notable stereodynamical effects in differential cross sections were observed. Quantum dynamics calculations revealed that strong constructive interference in the perpendicular configuration plays an important role in the stereodynamical effects observed.

Ultraviolet Photodissociation Reveals the Molecular Mechanism of Crown Ether Microsolvation Effect on the Gas-Phase Native-like Protein Structure.

Maintaining the protein high-order structures and interactions during the transition from aqueous solution to gas phase is essential to the structural analysis of native mass spectrometry (nMS). Herein, we systematically interrogate the effects of charge state and crown ether (CE) complexation on the gas-phase native-like protein structure by integrating nMS with 193 nm ultraviolet photodissociation (UVPD). The alterations of photofragmentation yields of protein residues and the charge site distribution of fragment ions reveal the specific sites and sequence regions where charge and CE take effect. Our results exhibit the CE complexation on protonated residues can largely alleviate the structure disruption induced by the intramolecular solvation of charged side chains. The influences of CE complexation and positive charge on gas-phase protein structure exhibit generally opposite trends because the CE microsolvation avoids the hydrogen-bonding formation between the charged side chains with backbone carbonyls. Thus, CE complexation leads to a more stable and native-like protein structure in the gas phase.

Motif-dependent immune co-receptor interactome profiling by photoaffinity chemical proteomics.

Identification of the tyrosine phosphorylation (pY)-dependent interactome of immune co-receptors is crucial for understanding signal pathways involved in immunotherapy. However, identifying the motif-specific interactome for each pY commonly found on these multi-phosphorylated membrane proteins remains challenging. Here, we describe a photoaffinity-based chemical proteomic approach to dissect the motif-specific cytoplasmic interactomes of the critical immune co-receptor CD28. Various full-length CD28 cytoplasmic tails (CD28cyto) with defined pY and selectively replaced photo-methionine were synthesized and applied to explore three pY-motif-dependent CD28cyto interactomes. We identified a stand-alone interaction of phospholipase PLCG1 with the Y191 motif with enhanced affinity for the sequence neighboring the transmembrane domain. Importantly, taking advantage of native top-down mass spectrometry with a 193-nm laser, we discovered the direct association of a previously undefined pY218 motif with the kinase PKCθ through its C2 domain. This synthetic CD28cyto-based photoaffinity proteomic approach is generically applicable to the study of other immune co-receptors with multiple pY sites on their linear cytoplasmic tail.

Chloride-Mediated Peroxide-Free Photochemical Oxidation of Proteins (PPOP) in Mass Spectrometry-Based Structural Analysis.

Ultraviolet (UV) laser photolysis of hydrogen peroxide (H2O2) for the in situ generation of hydroxyl radicals (•OH) is a widely utilized strategy in the oxidation footprinting of native proteins and mass spectrometry (MS)-based structural analysis. However, it remains challenging to realize peroxide-free photochemical oxidation footprinting. Herein, we describe the footprinting of native proteins by chloride-mediated peroxide-free photochemical oxidation of proteins (PPOP). The protein samples are prepared within biocompatible phosphate-buffered saline (PBS) containing 10 mM Gln as radical scavengers and oxidized in a capillary flow reactor directly under a single-pulse (10 ns) irradiation of a 193 nm ArF UV laser. The main oxidized protein residues are CMYWFHLI. We demonstrate that the PPOP-MS strategy is highly sensitive to the protein high-order structures and can be applied to monitor the protein-drug interfaces, which provides a promising footprinting alternative for protein structure-function explorations.

Photochemical bromination and iodination of peptides and proteins by photoexcitation of aqueous halides.

Although halogen atoms can greatly improve the stability, selectivity, and bioactivity of proteins, direct halogenation of proteins or peptides by chemical strategy has been never achieved. Herein, we describe the developments of direct photochemical bromination and iodization of unprotected proteins and peptides in the direct irradiation device and the single-pulsed irradiation capillary reactor with biocompatible aqueous halides Br- and I-, respectively. These novel photochemical modifications are triggered by 193 nm laser photoexcitation of commonly photo-inert halide ions to form active radical species. High protein modification efficiency (>90%) can be achieved under just 10 ns ultra-short irradiation of a single pulse of laser shot while the compact native protein structure could be largely retained. The specifically modified residues are Tyr, His, Trp for bromination and Tyr, His for iodization. The photochemical halogenation sites and rates are highly selective to protein native structures, providing dynamic insights into protein structure alterations and protein-drug interfaces in human serum protein (HSA)-warfarin interaction. This novel 193 nm photochemical strategy opens new opportunities for the protein structure-function explorations.

Improving the performance of proteomic analysis via VAILase cleavage and 193-nm ultraviolet photodissociation.

Further improving the proteomic identification coverage and reliability is still challenging in the mass spectrometry (MS)-based proteomics. Herein, we combine VAILase and trypsin digestion with 193-nm ultraviolet photodissociation (UVPD) and higher-energy collision dissociation (HCD) to improve the performance of bottom-up proteomics. As VAILase exhibits high complementarity to trypsin, the proteome sequence coverage is improved obviously whether with HCD or 193-nm UVPD. The high diversity of fragment ion types produced by UVPD contributes to the improvements of identification reliability for both trypsin- and VAILase-digested peptides with an average XCorr score improvement of 10%.

'Seven-step two-lobe' HoLEP: a modification to gain efficiency of the enucleation applying relatively low-power holmium laser devices.

PURPOSE: In order to increase the efficiency of the low-power holmium laser enucleation of the prostate (LP-HoLEP), and introduce it as a standard surgery for BPH, we described a modified 'seven-step two-lobe' HoLEP (ST HoLEP) technique applying 60-W device in a stepwise manner. METHODS: From July 2016 to August 2019, 120 patients who received LP-HoLEP at our hospital because of urinary tract symptoms caused by BPH were included in the study. The patients were assigned into two groups, 60 consecutive patients received modified ST HoLEP compared with another preexisting 60 consecutive patients who received the conventional three-lobe HoLEP (T HoLEP) before the technical modification. The clinical parameters, including patient characteristics, perioperative data, as well as voiding outcomes, and complications were evaluated after at least 3-month follow-up. RESULTS: The median enucleation efficiency of the ST HoLEP was 0.72 gm/min, which was significantly higher than 0.62 gm/min of the T HoLEP. Despite the preoperative IPSS was slightly higher in T HoLEP group, the other preoperative and perioperative data showed no statistical difference between the two groups. After ST HoLEP procedure, the urinary incontinence rate was continually improved at 1-week, 1-month, and 3-month follow-up which were 13.3%, 6.7%, and 1.7%, respectively. There was no significant difference in postoperative voiding outcomes and urinary continence results in 3-month follow-up. CONCLUSION: The ST HoLEP technique was proved to increase the efficiency which was benefit from minimizing the surgical incision, facilitating the single surgical plane identification and maintenance during the whole enucleation procedure.

Temperature- and pressure-dependent rate coefficient measurement for the reaction of CH2OO with CH3CH2CHO.

Propionaldehyde is one of the most abundant aldehydes, which are an important class of volatile organic compounds. In this work, the rate coefficient of the reaction of the simplest Criegee intermediate CH2OO with propionaldehyde (CH3CH2CHO) was measured for the first time in a flash photolysis reaction tube by using the OH laser-induced fluorescence (LIF) method at temperature and pressure in the range of 283 to 318 K and 5 to 200 Torr. This reaction is observed to be pressure- and temperature-dependent. The measured rate coefficient at 50 Torr is in the vicinity of the high-pressure limit value of (3.23 ± 0.49) × 10-12 cm3 s-1 at 298 K, which is in agreement with a previously reported theoretical result of 2.44 × 10-12 cm3 s-1. The Arrhenius plot of the temperature-dependent rate coefficients yields an activation energy of (-1.99 ± 0.23) kcal mol-1.

A crossed molecular beam apparatus with multi-channel Rydberg tagging time-of-flight detection.

We report a new crossed molecular beam apparatus with the H atom Rydberg tagging detection technique. The multi-channel detection scheme with 15 microchannel plate (MCP) detectors enables simultaneously accumulating time-of-flight spectra over a wide range of scattering angles (112°). The efficiency of data acquisition has been enhanced by an order of magnitude. The angular distribution of H atoms from photodissociation of CH4 at 121.6 nm was used for calibrating the detection efficiency of different MCP detectors. The differential cross section of the reaction F + H2 → HF + H at the collision of 6.9 meV was measured, demonstrating the feasibility and accuracy of this multi-channel detection method. This apparatus could be a powerful tool for investigating the dynamics of reactions at very low collision energy.

Kinetic Studies for the Reaction of syn-CH3CHOO with CF3CH═CH2.

Hydrofluoroolefins (HFOs, CxF2x+1CH═CH2) have great potential to replace hydrofluorocarbons (HFCs) as refrigerants. Here the kinetics for the reaction of syn-CH3CHOO with CF3CH═CH2 (HFO-1243zf), the simplest of HFOs, have been studied in a flash photolysis flow reactor at a total pressure of 50 Torr, by using the OH laser-induced fluorescence (LIF) method. The bimolecular reaction rate coefficients were measured at temperatures ranging from 283 to 318 K. A weak positive temperature dependence was observed, with an activation energy of 1.41 ± 0.12 kcal mol-1. At 298 K, the measured rate coefficient was (2.42 ± 0.51) × 10-14 cm3 s-1, in the vicinity of the previously reported upper limit value for the reaction of CH2OO with CF3CH═CH2.

Single-Atom Pt+ Derived from the Laser Dissociation of a Platinum Cluster: Insights into Nonoxidative Alkane Conversion.

In this study, we construct a 193 nm ultraviolet laser dissociation high-resolution mass spectrometry (HRMS) platform to produce Pt+ cations with high efficiency, which is in situ applied for monitoring the "Pt+ + alkanes" reactions (where alkanes include methane, ethane, and propane). The conversion intermediates and products could be accurately determined by an orbitrap detector with high resolution (up to 150 000). Importantly, methane conversion by Pt+ cations yields [Pt + ethane]+ and [Pt + ethylene]+ as the sole products formed via the cross-coupling reaction of the Pt-CH2 intermediate with gaseous methane. However, the Pt+ cations promote only the nonoxidative dehydrogenation of ethane and propane to give the corresponding [Pt + alkenes]+ and [Pt + alkynes]+. The details of the reaction mechanism are corroborated by density functional theory (DFT) calculations. These results highlight the power of HRMS with the laser dissociation of metal clusters in the generation and reaction characterization of metal ions.

Vibrational overtone excitation of D2 in a molecular beam with a high-energy, narrow-bandwidth, nanosecond optical parametric oscillator/amplifier.

We have built a high-energy, narrow-bandwidth, nanosecond light source for efficient preparation of vibrationally excited molecules in a molecular beam. It consists of an injection-seeded optical parametric oscillator and two optical parametric amplifiers. Pumped by the second harmonic of a commercial injection-seeded Nd:YAG laser, it can generate pulse energies up to 377 mJ at 655 nm with a bandwidth smaller than 200 MHz. Its stability is excellent, with a standard deviation of pulse energy of 5.2 mJ and a wavelength stability of 0.001 cm-1. We demonstrated this light source in a crossed-molecular-beam experiment of the H + D2 (v = 2, j = 0) → HD + D reaction, in which it was used for overtone excitation of D2 molecules from (v = 0, j = 0) to (v = 2, j = 0) with an overall excitation efficiency of 2.5%.