Direct Insertion Research Articles

Carbenoids with Sulfinate as Nucleofuge for Matteson‐Type Homologation: Direct Insertion of Oxygen‐ and Nitrogen‐Substituted Units into Carbon‐Boron Bonds

AbstractCarbenoid insertion into boronate carbon‐boron bonds, namely the Matteson‐type homologation, has been recognized as a powerful tool for constructing carbon‐carbon bonds. However, some limitations and inconvenience still exist with the carbenoids currently employed, such as the use of highly cryogenic and basic conditions. Herein, we report a new class of stable carbenoids with sulfinate as nucleofuge for Matteson‐type homologations, which directly introduce O‐ and N‐substituted methylenes into carbon‐boron bonds. Enabled by oxazaborolidines as the boronic substrates, the reaction is operatable at 0 °C or room temperature with weaker bases. Broad functional groups, including acidic C−H bonds, can be tolerated. The synthetic utility of this method has been demonstrated in the gram‐scale synthesis and iterative insertion of various carbenoids.

Carbenoids with Sulfinate as Nucleofuge for Matteson-Type Homologation: Direct Insertion of Oxygen- and Nitrogen-Substituted Units into Carbon-Boron Bonds.

Carbenoid insertion into boronate carbon-boron bonds, namely the Matteson-type homologation, has been recognized as a powerful tool for constructing carbon-carbon bonds. However, some limitations and inconvenience still exist with the carbenoids currently employed, such as the use of highly cryogenic and basic conditions. Herein, we report a new class of stable carbenoids with sulfinate as nucleofuge for Matteson-type homologations, which directly introduce O- and N-substituted methylenes into carbon-boron bonds. Enabled by oxazaborolidines as the boronic substrates, the reaction is operatable at 0 °C or room temperature with weaker bases. Broad functional groups, including acidic C-H bonds, can be tolerated. The synthetic utility of this method has been demonstrated in the gram-scale synthesis and iterative insertion of various carbenoids.

Three-dimensional source position verification in image-guided high-dose-rate brachytherapy using an XCT-based gel dosimeter.

Comprehensive quality assurance (QA) for a seamless workflow of high-dose-rate brachytherapy, from imaging to planning and irradiation, is uncommon, and QA of the source dwell position is performed in one- or two-dimensions. Gel dosimetry using magnetic resonance imaging (MRI) is effective in verifying the three-dimensional distribution of doses for image-guided brachytherapy (IGBT). However, MRI scanners are not readily accessible, and MRI scanning is time-consuming. Nevertheless, X-ray computed tomography (XCT) is available for IGBT planning. In this study, we designed and developed an efficient method for QA for a seamless workflow of IGBT with a new commercially available XCT-based polymer gel dosimeter. To enable direct insertion of brachytherapy applicators, the gelatinizing agent of the dosimeter was modified. A cylindrical polyvinyl chloride jar was filled with the modified gel dosimeter, which was subsequently used to determine the reproducibility of source dwell positions, detectability of source positional errors from intentionally introduced catheter length offsets, effect of looped source transfer tubes on the average displacement, extent of inter-observer variation, and gel robustness following multiple needle-insertions. Three ProGuide sharp needles were inserted into the jar. The dwell time at each point was determined to identify the irradiated volume with a diameter of approximately 10mm on XCT images. All the times were the same. The plan was delivered using an afterloader with an Ir-192 radioactive source, and the irradiated gel dosimeter was scanned using an XCT scanner. The subtracted images were generated from pre- and post-irradiated images. Volumes with incremented Hounsfield units were manually identified and contoured. The centroid of the volume was defined as the measured source dwell position. Subsequently, planned source dwell positions were extracted from the DICOM file of the plan. Finally, the source dwell positions in plan and irradiated gel were compared in three axes. The hardness of the dosimeter was 1250% greater than that of the previously reported gel dosimeter. Source dwell positions were visually identified in the XCT image. Testing of CT acquisition, planning, irradiation, and analysis was completed in approximately 1h. In the reproducibility test of source dwell positions, created by inserting three needles (each with three source dwell positions), the average displacements of the source positions from the first source dwell position were within 0.5mm in all three directions. In the detectability test, displacements were less than 1mm in the x-y plane but greater than 1mm in the z-axis, which was the source path direction. When errors of 1-3mm were intentionally introduced, the measured displacement was within 0.7mm of the median (range: 0.21-1.65mm) of intentional errors. When the transfer tube was looped, the source dwell position displaced by approximately 1mm. After 20 needle-insertions, the source dwell position displacement was within 1mm. The maximum inter-observer variation of contouring was 0.57mm. The XCT-based gel dosimeter enabled verification of three-dimensional source dwell positions for a seamless workflow of IGBT with high precision and efficiency.

Direct oxygen insertion into C-C bond of styrenes with air.

Skeletal editing of single-atom insertion to basic chemicals has been demonstrated as an efficient strategy for the discovery of structurally diversified compounds. Previous endeavors in skeletal editing have successfully facilitated the insertion of boron, nitrogen, and carbon atoms. Given the prevalence of oxygen atoms in biologically active molecules, the direct oxygenation of C-C bonds through single-oxygen-atom insertion like Baeyer-Villiger reaction is of particular significance. Herein, we present an approach for the skeletal modification of styrenes using O2 via oxygen insertion, resulting in the formation of aryl ether frameworks under mild reaction conditions. The broad functional-group tolerance and the excellent chemo- and regioselectivity are demonstrated in this protocol. A preliminary mechanistic study indicates the potential involvement of 1,2-aryl radical migration in this reaction.

Asymmetric Total Synthesis of Naturally Occurring (R)-2'-Methoxydihydroartemidin, (R)-(E)-3'-Hydroxyartemidin, and Its Structural Congeners: Method Optimization and Mechanistic Analysis.

Asymmetric total synthesis of naturally occurring 3-substituted isocoumarins, 2'-methoxydihydroartemidin, (E)-3'-hydroxyartemidin, and two structural congeners is reported in this article. Enantiopure 3-alkylisocoumarin core present in those target molecules was accessed through an atom-economical and regiodefined 6-endo-dig cyclization from properly substituted 2-halobenzoic acids and chiral terminal alkynes through ligand-free Cu(I) catalysis. A detailed mechanistic investigation was carried out through control experiments, and density functional theory (DFT) analysis reveals that solvent directed a non-Sonogashira pathway through direct insertion of alkyne through a regiodefined way is operating. The synthesized 3-alkylisocoumarins are synthetically manipulated into various small molecular entities.

An open comparative randomized prospective study: Direct trocar insertion vs Veress needle technique in laparoscopic surgeries.

Laparoscopy is a minimally invasive technique utilized for both diagnostic and surgical approaches. Minimally invasive procedures compared to laparotomy offer the advantages of reduced hospital stay, lower morbidity, decreased pain, and faster recovery. Common methods for laparoscopic entry include Veress needle insertion (VNI), direct optical trocar entry, direct trocar insertion (DTI), and the Hasson technique. This study aims to compare the efficacy and safety of VNI and DTI in laparoscopic gynecological surgeries. An open comparative randomized prospective study was conducted involving 200 women aged 18 to 70 years, scheduled for laparoscopic surgery at 2 tertiary centers. Participants were randomized into 2 groups: 1 using VNI and other using DTI. The groups were homogeneous regarding age, parity, and body mass index. The mean age of the VNI group is 45.22 ± 11.65 and the DTI group is 44.89 ± 10.5 (P = .833). There were no statistical significance in terms of the presence of chronic diseases and history of previous abdominal surgery between the groups (P = .802 and P = .510, respectively). Entry time to the abdomen, the decrease in hemoglobin values, and hospitalization length were found to be statistically significant between the entry methods (P < .001, P = .002, and P < .001, respectively). Entry time, the decrease in hemoglobin value, and hospitalization length were higher in the VNI group. In conclusion, although there is no definitive consensus on the optimal laparoscopic entry technique, direct trocar entry is an effective alternative to the Veress needle insertion technique. Direct trocar entry is associated with shorter entry times, fewer perioperative complications, less reduction in hemoglobin levels, and shorter hospitalization duration compared to VNI.

Minimum Energy Atomic Deposition: A novel, efficient atomistic simulation method for thin film growth

Thin-film growth is an area of research concerned with complex phenomena happening at atomic scales. Therefore, molecular simulation has been an important tool to confront experimental results to theoretical assumptions. However, the traditional thin film growth simulation methods, i.e., Molecular Dynamics (MD) and kinetic Monte-Carlo (kMC) and combinations thereof, suffer from limitations inherent to their design, i.e., limitations in system size and simulation time for MD and predetermined reaction rates and reaction sites for kMC. Consequently, it is practically impossible to simulate the evolution of polycrystalline growth resulting in ∼100nm thick films with realistic stress fields and defect structures, such as grain boundaries, stacking faults, etc. In this work, we propose a versatile and efficient atomistic simulation method (Minimum Energy Atomic Deposition) which works by direct insertion of atoms at points of minimal potential energy through efficient scanning of candidate positions and rapid relaxation of the system. This method allows simulating ≥100nm film thickness while mimicking experimental growth rates and high crystallinity and low-defect concentration and enables in-depth studies of atomic growth mechanisms, the evolution of crystal defects, and residual stress build-up. We demonstrate the efficiency and versatility of the method through the deposition of Al on Si, Al on Al, and Si on Si. The simulation results are systematically compared with experimental observations of thin-film deposition, yielding consistent observations. The method has been implemented in open-source LAMMPS software, making it easily accessible to the research community.

Evolution of [formula omitted]-spacing in clay with PEG bulk volume fraction and molecular weight: Theoretical and experimental study

In the pursuit of ensuring the sustainability of the construction sector and fortifying its resilience against climate change, scientists have dedicated significant efforts to explore new classes of innovative, affordable, and technologically advanced materials that exhibit high efficiency, thereby securing the future for generations to come. In this context, we have opted to produce clay-polymer ecosystems through the direct insertion process. The PEG2000/clay and PEG6000/clay composites underwent analysis using X-ray diffraction (XRD) techniques, revealing the evolution of dhklconcerning the PEG bulk volume fraction. The results indicate the presence of two adsorption cycles, each comprising three stages (dilute, two-dimensional semi-dilute, and plateau). Each cycle delineates the incorporation of a polymer layer into the interlayer spaces of clay minerals. To elucidate this adsorption process, we have proposed a model depicting PEG chain conformation in confined spaces, represented as both monolayer and bilayer configurations. The influence of PEG molecular weight is distinctly evident in the dhklevolution across various clay categories. Ultimately, the application of scaling theory to model the experimental results proves to be robust, offering a precise description of the three discussed regimes.

Mechanically adaptive and deployable intracortical probes enable long-term neural electrophysiological recordings

Flexible intracortical probes offer important opportunities for stable neural interfaces by reducing chronic immune responses, but their advances usually come with challenges of difficult implantation and limited recording span. Here, we reported a mechanically adaptive and deployable intracortical probe, which features a foldable fishbone-like structural design with branching electrodes on a temperature-responsive shape memory polymer (SMP) substrate. Leveraging the temperature-triggered soft-rigid phase transition and shape memory characteristic of SMP, this probe design enables direct insertion into brain tissue with minimal footprint in a folded configuration while automatically softening to reduce mechanical mismatches with brain tissue and deploying electrodes to a broader recording span under physiological conditions. Experimental and numerical studies on the material softening and structural folding-deploying behaviors provide insights into the design, fabrication, and operation of the intracortical probes. The chronically implanted neural probe in the rat cortex demonstrates that the proposed neural probe can reliably detect and track individual units for months with stable impedance and signal amplitude during long-term implantation. The work provides a tool for stable neural activity recording and creates engineering opportunities in basic neuroscience and clinical applications.

Evaluation of a novel central venous access port for direct catheter insertion without a peel-away sheath.

This study retrospectively evaluated the feasibility and safety of implanting a newly developed central venous access port (CV-port) that allows catheter insertion into a vein without the use of a peel-away sheath, with a focus on its potential to minimize risks associated with conventional implantation methods. All procedures were performed using a new device (P-U CelSite Port™ MS; Toray Medical, Tokyo, Japan) under ultrasound guidance. The primary endpoint was the implantation success rate. The secondary endpoints were the safety and risk factors for infection in the early postprocedural period (< 30days). We assessed 523 CV-port implantations performed in a cumulative total of 523 patients (240 men and 283 women; mean age, 61.6 ± 13.1years; range, 18-85years). All implantations were successfully performed using an inner guide tube and over-the-wire technique through 522 internal jugular veins and one subclavian vein. The mean procedural time was 33.2 ± 10.9min (range 15-112min). Air embolism, rupture/perforation of the superior vena cava, or hemothorax did not occur during catheter insertion. Eleven (2.1%) intraprocedural complications occurred, including Grade I arrhythmia (n = 8) and subcutaneous bleeding (n = 1), Grade II arrhythmia (n = 1), and Grade IIIa pneumothorax (n = 1). Furthermore, 496 patients were followed up for ≥ 30days. Six early postprocedural complications were encountered (1.1%), including Grade IIIa infection (n = 4), catheter occlusion (n = 1), and skin necrosis due to subcutaneous leakage of trabectedin (n = 1). These six CV-ports were withdrawn, and no significant risk factors for infection in the early postprocedural period were identified. The implantation of this CV-port device demonstrated comparable success and complication rates to conventional devices, with the added potential benefit of eliminating complications associated with the use of a peel-away sheath.

Unexpected E-to-Z Isomerizations during the Negishi-Type Homocoupling of E-Iodoalkenes.

The direct insertion of Zn into olefin-halide bonds is a challenge. When (E)-alkenyl iodides were treated with a very large excess of Zn nanoparticles, in the presence of Pd(PPh3)4, the dimerization was observed but, unexpectedly, yielding mainly Z,E-1,3-dienes. This apparently contrathermodynamic E-to-Z isomerization of organometallic intermediates is predicted to be general and is explained with the aid of DFT [principally M06/6-311+G(d,p)], MP2, and CCSD(T) calculations.

Comparison of three umbilical entry sites for intraperitoneal access by the direct trocar insertion technique: a randomized pilot study.

The most effective methods and entry sites for laparoscopic surgery remain a subject of ongoing investigation and discussion. The purpose of the study was to analyze and compare three umbilical entry sites for intraperitoneal access using the direct trocar insertion technique. A randomized pilot study was conducted between March 2021 and January 2023, involving women eligible for laparoscopic gynecological surgery. The women were allocated to one of three equally sized groups based on trocar entry points: subumbilical, supraumbilical, or umbilical. Success and failure rates of trocar entry, factors influencing success or failure, and early and late complications were systematically evaluated and compared across groups. A total of 243 patients, with a mean age of 32.93±8.33 years, were included in three groups of 81 each. Trocar entry success rates were 97.5%, 89.2%, and 89.5% in the supraumbilical, umbilical, and subumbilical groups, respectively (p>0.05). Failed trocar entry was significantly associated with age, gravidity, body mass index (BMI), waist circumference, hip circumference, and abdominal subcutaneous fat thickness (p<0.001). Regression analysis revealed that, in the subumbilical group, higher gravidity [odds ratios (OR): 0.390, 95% confidence interval (CI): 0.174-0.872, p=0.022) and greater abdominal subcutaneous fat thickness (OR: 0.090, 95% CI: 0.019-0.431, p=0.03) were associated with lower odds of successful trocar entry. In contrast, in the umbilical group, a higher waist circumference was associated with lower odds of successful trocar entry (OR: 0.673, 95% CI: 0.494-0.918, p=0.012). None of the covariates were significant in the supraumbilical group. The study highlighted the importance of selecting the appropriate trocar entry site in laparoscopic gynecological surgery. Surgeons should consider factors such as age, gravidity, BMI, waist circumference, hip circumference, and abdominal subcutaneous fat thickness, as these factors significantly influence the success of trocar entry.

Dirhodium(II)/ XantPhos Catalyzed Synthesis of β-(E)-Vinylsilanes via Hydrosilylation and Isomerization from Alkynes.

A concise hydrosilylation of alkynes for synthesizing β-(E)-vinylsilanes catalyzed by dirhodium(II)/XantPhos has been developed. In this reaction, β-(E)-vinylsilanes were generated from the isomerization of β-(Z)-vinylsilanes catalyzed by dirhodium(II) hydride species rather than the direct insertion of triple bond into M-H or M-Si bond (traditional Chalk-Harrod mechanism or modified Chalk-Harrod mechanism). The hydrosilylation displayed a broad substrate scope for alkynes and tertiary silanes, tolerating diverse functional groups including halides, nitrile, amines, esters, and heterocycles.

Visible Light Induced B-H Bond Insertion Reaction with Diazo Compounds.

A protocol induced by visible light for the direct insertion of α-carbonyl carbenes into the B-H bond of amine-borane adducts has been developed under conditions that are free of metal and photocatalyst. This approach provides a straightforward route to various organoboron compounds from diazo compounds and amine-borane adducts with moderate to good yields. Mechanistic investigations reveal that this photoinduced reaction proceeds through concerted carbene insertion into the B-H bond, and the photoinduced generation of free carbene from α-diazo esters may be the rate-determining step.

Direct Mass Spectrometric Analysis of Brominated Flame Retardants in Synthetic Polymers.

Brominated flame retardants (BFRs) are persistent organic pollutants that pose a major threat to the environment. In this study, a direct insertion probe (DIP) coupled with atmospheric pressure chemical ionization (APCI) quadrupole time-of-flight mass spectrometry (QTOF-MS) was used to characterize additives, especially BFRs, from solid polymer samples with minimal sample preparation. A temperature-programmed DIP analysis, from 150 to 450 °C within 10 min, was utilized to achieve temporal separation of analytes based on their boiling or degradation temperatures, thereby facilitating their easier identification within a single run. Studied BFRs showed different behaviors during the analysis: decabromodiphenyl ether and tetrabromobisphenol A were found to be stable within the studied temperature range, while hexabromocyclododecane already started to debrominate. Our study showed that the DIP-APCI-MS method suited well for the direct qualitative identification of BFRs from polymer matrices. Furthermore, by optimizing the sampling procedure with cryogenic grinding, even quantitative analysis could be performed. The DIP measurements also provided important information about the composition of polymer matrices, including the identification of the comonomers present. Overall, DIP-APCI QTOF-MS was found to be an excellent tool for the compositional analysis of plastic samples. Developing rapid and reliable analysis methods can pave the way for more efficient plastic recycling and the safer use of plastic recyclates.

Lunar flyby transfers to TianQin configuration

The TianQin mission for gravitational wave detection consists of three drag-free spacecrafts deployed in geocentric orbits, and forms an equilateral triangle configuration. In this paper, we investigate lunar flyby transfers to the TianQin configuration. Firstly, a preliminary design method of lunar flyby transfers is proposed in the patched-conic model. Then, lunar flyby transfers in the ephemeris model are constructed through the multiple shooting method. Numerical computation shows that compared to the traditional Hohmann transfer, the lunar flyby transfer can save about 12% of fuel, but its time of flight increases to about 11 days. For the initial deployment of the TianQin configuration, we propose two methods, the phasing method and the direct insertion method. The phasing method uses the phase adjustment when the three spacecraft reach the target orbit. Numerical calculation indicates that the fuel costs of the three spacecraft are identical to that of the nominal transfer, and the total time of flight is about 17 days. Then, the Jet transport tool is applied to find appropriate separation impulses to design the direct insertion orbits. Numerical computation shows that compared to the phasing method, the fuel cost of the direct insertion method is slightly larger than that of the phasing method, but the time of flight of the former is about 5 days shorter than that of the latter.

Preemptive Direct Aortic Insertion of Impella 5.5 in Patients Undergoing Cardiac or Aortic Surgery

Preemptive Direct Aortic Insertion of Impella 5.5 in Patients Undergoing Cardiac or Aortic Surgery

A bioadhesive pacing lead for atraumatic cardiac monitoring and stimulation in rodent and porcine models.

Current clinically used electronic implants, including cardiac pacing leads for epicardial monitoring and stimulation of the heart, rely on surgical suturing or direct insertion of electrodes to the heart tissue. These approaches can cause tissue trauma during the implantation and retrieval of the pacing leads, with the potential for bleeding, tissue damage, and device failure. Here, we report a bioadhesive pacing lead that can directly interface with cardiac tissue through physical and covalent interactions to support minimally invasive adhesive implantation and gentle on-demand removal of the device with a detachment solution. We developed 3D-printable bioadhesive materials for customized fabrication of the device by graft-polymerizing polyacrylic acid on hydrophilic polyurethane and mixing with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to obtain electrical conductivity. The bioadhesive construct exhibited mechanical properties similar to cardiac tissue and strong tissue adhesion, supporting stable electrical interfacing. Infusion of a detachment solution to cleave physical and covalent cross-links between the adhesive interface and the tissue allowed retrieval of the bioadhesive pacing leads in rat and porcine models without apparent tissue damage. Continuous and reliable cardiac monitoring and pacing of rodent and porcine hearts were demonstrated for 2 weeks with consistent capture threshold and sensing amplitude, in contrast to a commercially available alternative. Pacing and continuous telemetric monitoring were achieved in a porcine model. These findings may offer a promising platform for adhesive bioelectronic devices for cardiac monitoring and treatment.

Extended Regression Analysis for Debye-Einstein Models Describing Low Temperature Heat Capacity Data of Solids.

Heat capacity data of many crystalline solids can be described in a physically sound manner by Debye-Einstein integrals in the temperature range from 0K to 300K. The parameters of the Debye-Einstein approach are either obtained by a Markov chain Monte Carlo (MCMC) global optimization method or by a Levenberg-Marquardt (LM) local optimization routine. In the case of the MCMC approach the model parameters and the coefficients of a function describing the residuals of the measurement points are simultaneously optimized. Thereby, the Bayesian credible interval for the heat capacity function is obtained. Although both regression tools (LM and MCMC) are completely different approaches, not only the values of the Debye-Einstein parameters, but also their standard errors appear to be similar. The calculated model parameters and their associated standard errors are then used to derive the enthalpy, entropy and Gibbs energy as functions of temperature. By direct insertion of the MCMC parameters of all 4·105 computer runs the distributions of the integral quantities enthalpy, entropy and Gibbs energy are determined.

Dynamic thresholding logarithmic companding for PAPR reduction in MIMO-OFDM systems for 5G wireless communication

In order to advance 5G wireless communication technology, this paper presents a novel method for lowering the Peak-to-Average Power Ratio (PAPR) in Multiple-Input Multiple-Output Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) systems. It is called the Dynamic Thresholding-based μ-law (DT-μ-law) logarithmic companding technique, and it greatly improves the performance of the system by effectively broadcasting data streams on a single frequency across multiple channels. This technique's ability lies in compressing the amplitude of the transmitting signal beyond a specific threshold value before the parallel-to-serial conversion block in the MIMO-OFDM system. It employs the direct insertion of an offset value into the guard bits, rather than using a step function for the amplitude reduction process, which can reduce additional system complexity and data loss during signal expansion at the receiver end. This technique is more adequately suited for dynamic data rate shifting and interference within a limited threshold value. The dynamic thresholding value (α) is determined by calculating the median and standard deviation of the μ-law companding. This ensures the effective compression of higher amplitude signals at the transmitter, using μ-law log companding. To streamline the decompanding process at the receiver, an offset is introduced, facilitating a smoother transition and reducing complexity. The results demonstrate that the proposed DT- μ-law companding technique significantly improves PAPR reduction while maintaining low Bit Error Rates (BER) and high average spectral power efficiency. This efficiency is optimal when the μ value is maintained within the range of 4–4.5. Furthermore, it was observed that an increase in the μ value corresponds to a decrease in both PAPR value and BER. Specifically, at a signal-to-noise ratio of 15.2 dB, the BER stabilizes at 10−1. Compared to existing methods like the Max-Min Decomp-SLM approach, this technique offers lower Signal-to-Noise Ratio (SNR) values, thereby enhancing spectral efficiency and maximizing data capacity.