Flow reduction due to arterial catheterization during stroke treatment - A computational study using a distributed compartment model.

The effectiveness of various stroke treatments depends on the anatomical variability of the cerebral vasculature, particularly the collateral blood vessel network. Collaterals at the level of the Circle of Willis and distal collaterals, such as the leptomeningeal arteries, serve as alternative avenues of flow when the primary pathway is obstructed during an ischemic stroke. Stroke treatment typically involves catheterization of the primary pathway, and the potential risk of further flow reduction to the affected brain area during this treatment has not been previously investigated. To address this clinical question, we derived the lumped parameters for catheterized blood vessels and implemented a corresponding distributed compartment (0D) model. This 0D model was validated against an experimental model and benchmark test cases solved using a 1D model. Additionally, we compared various off-center catheter trajectories modeled using a 3D solver to this 0D model. The differences between them were minimal, validating the simplifying assumption of the central catheter placement in the 0D model. The 0D model was then used to simulate blood flows in realistic cerebral arterial networks with different collateralization characteristics. Ischemic strokes were modeled by occlusion of the M1 segment of the middle cerebral artery in these networks. Catheters of different diameters were inserted up to the obstructed segment and flow alterations in the network were calculated. Results showed up to 45% maximum blood flow reduction in the affected brain region. These findings suggest that catheterization during stroke treatment may have a further detrimental effect for some patients with poor collateralization.

Simulated skin model for in vitro evaluation of insertion performance of microneedles: design, development, and application verification.

Microneedles, as a new efficient and safe transdermal drug delivery technology, has a wide range of applications in drug delivery, vaccination, medical cosmetology, and diagnostics. The degree of microneedles penetration into the skin determines the reliability of the delivery dose, but its evaluation is not yet well-established, which is one of the major constraints in the commercialization of microneedles. In this paper, a novel visual simulated skin model was developed with reference to the physical properties of real skin. The simulated skin model was well-designed and its prescription was optimized to make the thickness, hardness, elasticity, and other parameters close to those of real skin. It not only meets the need to assess the degree of insertion of microneedles but also provides a visual observation of the insertion state of microneedles.

Advancing robot-guided techniques in lumbar spine surgery: a systematic review and meta-analysis.

BACKGROUND: Lumbar spine surgery is a crucial intervention for addressing spinal injuries or conditions affecting the spine, often involving lumbar fusion through pedicle screw (PS) insertion. The precision of PS placement is pivotal in orthopedic surgery. This systematic review compares the accuracy of robot-guided (RG) surgery with free-hand fluoroscopy-guided (FFG), free-hand without fluoroscopy-guided (FHG), and computed tomography image-guided (CTG) techniques for PS insertion. METHODS: A systematic search of various databases from 1 January 2013 to 30 December 2023 was conducted following PRISMA guidelines. Primary outcomes, including PS insertion accuracy and breach rate, were analyzed using a random-effects model. Risk of bias was assessed using the Newcastle-Ottawa Scale. RESULTS: The overall accuracy of PS insertion using RG, based on 37 studies involving 3,837 patients and 22,117 PS, is 97.9%, with a breach rate of 0.021. RG demonstrated superior accuracy compared to FHG and CTG, with breach rates of 3.4 and 0.015 respectively for RG versus FHG, and 3.8 and 0.026 for RG versus CTG. Additionally, RG was associated with reduced mean estimated blood loss compared to CTG, indicating improved safety. CONCLUSIONS: The RG is associated with enhanced accuracy of PS insertion and reduced breach rates over other methods. However, additional randomized controlled trials comparing these modalities are needed for further validation. PROSPERO REGISTRATION: CRD42023483997.

The IncC and IncX1 resistance plasmids present in multi-drug resistant Escherichia coli strains isolated from poultry manure in Poland.

The study describes the whole-genome sequencing of two antibiotic-resistant representative Escherichia coli strains, isolated from poultry manure in 2020. The samples were obtained from a commercial chicken meat production facility in Poland. The antibiotic resistance profile was characterized by co-resistance to ß-lactam antibiotics, aminoglycosides, and fluoroquinolones. The three identified resistance plasmids (R-plasmids), pECmdr13.2, pECmdr13.3, and pECmdr14.1, harbored various genes conferring resistance to tetracyclines (tetR[A]) for, aminoglycoside (aph, aac, and aad families), ß-lactam (blaCMY-2, blaTEM-176), sulfonamide (sul1, sul2), fluoroquinolone (qnrS1), and phenicol (floR). These plasmids, which have not been previously reported in Poland, were found to carry IS26 insertion elements, the intI1-integrase gene, and conjugal transfer genes, facilitating horizontal gene transfer. Plasmids pECmdr13.2 and pECmdr14.1 also possessed a mercury resistance gene operon related to transposon Tn6196; this promotes plasmid persistence even without antibiotic selection pressure due to co-selection mechanisms such as co-resistance. The chicken manure-derived plasmids belonged to the IncX1 (narrow host range) and IncC (broad host range) incompatibility groups. Similar plasmids have been identified in various environments, clinical isolates, and farm animals, including cattle, swine, and poultry. This study holds significant importance for the One Health approach, as it highlights the potential for antibiotic-resistant bacteria from livestock and food sources, particularly E. coli, to transfer through the food chain to humans and vice versa.

Genomic Characteristics of an Extensive-Drug-Resistant Clinical Escherichia coli O99 H30 ST38 Recovered from Wound.

Background: Antibiotic-resistant Escherichia coli is one of the major opportunistic pathogens that cause hospital-acquired infections worldwide. These infections include catheter-associated urinary tract infections (UTIs), ventilator-associated pneumonia, surgical wound infections, and bacteraemia. Objectives: To understand the mechanisms of resistance and prevent its spread, we studied E. coli C91 (ST38), a clinical outbreak strain that was extensively drug-resistant. The strain was isolated from an intensive care unit (ICU) in one of Kuwait's largest hospitals from a patient with UTI. Methods: This study used whole-genome sequencing (Illumina, MiSeq) to identify the strain's multi-locus sequence type, resistance genes (ResFinder), and virulence factors. This study also measured the minimum inhibitory concentrations (MIC) of a panel of antibiotics against this isolate. Results: The analysis showed that E. coli C-91 was identified as O99 H30 ST38 and was resistant to all antibiotics tested, including colistin (MIC > 32 mg/L). It also showed intermediate resistance to imipenem and meropenem (MIC = 8 mg/L). Genome analysis revealed various acquired resistance genes, including mcr-1, bla CTX-M-14, bla CTX-M-15, and bla OXA1. However, we did not detect bla NDM or bla VIM. There were also several point mutations resulting in amino acid changes in chromosomal genes: gyrA, parC, pmrB, and ampC promoter. Additionally, we detected several multidrug efflux pumps, including the multidrug efflux pump mdf(A). Eleven prophage regions were identified, and PHAGE_Entero_SfI_NC was detected to contain ISEc46 and ethidium multidrug resistance protein E (emrE), a small multidrug resistance (SMR) protein family. Finally, there was an abundance of virulence factors in this isolate, including fimbriae, biofilm, and capsule formation genes. Conclusions: This isolate has a diverse portfolio of antimicrobial resistance and virulence genes and belongs to ST38 O99 H30, posing a serious challenge to treating infected patients in clinical settings.

A newly identified IncY plasmid from multi-drug-resistant Escherichia coli isolated from dairy cattle feces in Poland.

Comprehensive whole-genome sequencing was performed on two multi-drug-resistant Escherichia coli strains isolated from cattle manure from a typical dairy farm in Poland in 2020. The identified strains are resistant to beta-lactams, aminoglycosides, tetracyclines, trimethoprim/sulfamethoxazole, and fluoroquinolones. The complete sequences of the harbored plasmids revealed antibiotic-resistance genes located within many mobile genetic elements (e.g., insertional sequences or transposons) and genes facilitating conjugal transfer or promoting horizontal gene transfer. These plasmids are hitherto undescribed. Similar plasmids have been identified, but not in Poland. The identified plasmids carried resistance genes, including the tetracycline resistance gene tet(A), aph family aminoglycoside resistance genes aph(3″)-lb and aph (6)-ld, beta-lactam resistance genes blaTEM-1 and blaCTX-M-15, sulfonamide resistance gene sul2, fluoroquinolone resistance gene qnrS1, and the trimethoprim resistance gene dfrA14. The characterized resistance plasmids were categorized into the IncY incompatibility group, indicating a high possibility for dissemination among the Enterobacteriaceae. While similar plasmids (99% identity) have been found in environmental and clinical samples, none have been identified in farm animals. These findings are significant within the One Health framework, as they underline the potential for antimicrobial-resistant E. coli from livestock and food sources to be transmitted to humans and vice versa. It highlights the need for careful monitoring and strategies to limit the spread of antibiotic resistance in the One Health approach. IMPORTANCE: This study reveals the identification of new strains of antibiotic-resistant Escherichia coli in cattle manure from a dairy farm in Poland, offering critical insights into the spread of drug resistance. Through whole-genome sequencing, researchers discovered novel plasmids within these bacteria, which carry genes resistant to multiple antibiotics. These findings are particularly alarming, as these plasmids can transfer between different bacterial species, potentially escalating the spread of antibiotic resistance. This research underscores the vital connection between the health of humans, animals, and the environment, emphasizing the concept of One Health. It points to the critical need for global vigilance and strategies to curb the proliferation of antibiotic resistance. By showcasing the presence of these strains and their advanced resistance mechanisms, the study calls for enhanced surveillance and preventive actions in both agricultural practices and healthcare settings to address the imminent challenge of antibiotic-resistant bacteria.

De Novo Synthesis of α-Ketoamides via Pd/TBD Synergistic Catalysis.

Precisely controlling the product selectivity of a reaction is an important objective in organic synthesis. α-Ketoamides are vital intermediates in chemical transformations and privileged motifs in numerous drugs, natural products, and biologically active molecules. The selective synthesis of α-ketoamides from feedstock chemicals in a safe and operationally simple manner under mild conditions is a long-standing catalysis challenge. Herein, an unprecedented TBD-switched Pd-catalyzed double isocyanide insertion reaction for assembling ketoamides in aqueous DMSO from (hetero)aryl halides and pseudohalides under mild conditions is reported. The effectiveness and utility of this protocol are demonstrated by its diverse substrate scope (93 examples), the ability to late-stage modify pharmaceuticals, scalability to large-scale synthesis, and the synthesis of pharmaceutically active molecules. Mechanistic studies indicate that TBD is a key ligand that modulates the Pd-catalyzed double isocyanide insertion process, thereby selectively providing the desired α-ketoamides in a unique manner. In addition, the imidoylpalladium(II) complex and α-ketoimine amide are successfully isolated and determined by X-ray analysis, confirming that they are probable intermediates in the catalytic pathway.

A phase II study of osimertinib in patients with NSCLC harboring EGFR exon 20 insertion: A multicenter trial of the Korean Cancer Study Group (LU17-19).

BACKGROUND: Epidermal growth factor receptor (EGFR) exon 20 insertions account for up to 10% of all EGFR mutations. Clinical outcomes in patients receiving approved EGFR exon 20 insertion-specific inhibitors have been variable. Although osimertinib has demonstrated antitumor activity in clinical trials, its clinical efficacy and translational potential remain to be determined in non-small cell lung carcinoma (NSCLC) with EGFR exon 20 insertion. METHODS: In this multicenter phase II study, patients with advanced NSCLC harboring EGFR exon 20 insertions for whom the standard chemotherapy failed received 80 mg osimertinib once daily. The primary endpoint was the investigator-assessed objective response rate (ORR) as defined by Response Evaluation Criteria in Solid Tumors version 1.1. The secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety profile. RESULTS: Among 15 patients enrolled at stage 1, the best response was most commonly disease stabilization (73.3 %), which did not meet the stage 1 threshold (objective response ≥ 2/15). As of data cutoff, two patients remained on the treatment. The median PFS and OS were 3.8 (95 % confidence interval [CI] = 1.7-5.5) months and 6.5 (95 % CI = 3.9-not reached) months, respectively. Adverse events (≥grade 3) were anemia, hypercalcemia, and pneumonia (13.3 % each), and asthenia, femur fracture, increased alkaline phosphate, hyperkalemia, bone pain, and azotemia (6.7 % each). Pre-existing EGFR C797S mutation detected in plasma limited the efficacy of osimertinib. CONCLUSION: Osimertinib at 80 mg once daily had limited efficacy and mostly showed disease stabilization with an acceptable safety profile in advanced NSCLC harboring EGFR exon 20 insertions. CLINICALTRIALS: govIdentifier: NCT03414814.

Molecular Detection of Coxiella burnetii in Vaginal Swab Samples from Sheep That Aborted.

Background: Coxiella burnetii, an obligate intracellular bacterium, is the etiological agent of Q fever in humans and one of the causes of abortion in small ruminants. Although coxiellosis is considered an exotic disease, there are a few reports in Mexico. Methods: The objective of this work was to determine the presence of C. burnetii DNA in vaginal samples from sheep that presented abortion and ram semen. A total of 180 vaginal exudate samples and 20 semen samples were obtained from five Central and Southern States of Mexico. Total DNA was extracted from vaginal swabs and C. burnetii was identified by PCR amplification and sequencing of the IS1111 insertion sequence. Results and Conclusion: In total, 110 (110/180) vaginal samples and 12 (12/20) semen samples were positive for C. burnetii. This is the first report of C. burnetii in sheep that aborted and in ram semen in Mexico.

Experimental Study of Needle Insertion into Gerbil Tympanic Membrane.

The perforation characteristics and fracture-related mechanical properties of the tympanic membrane (TM) greatly affect surgical procedures like myringotomy and tympanostomy performed on the middle ear. We analyzed the most important features of the gerbil TM perforation using an experimental approach that was based on force measurement during a 2-cycle needle insertion/extraction process. Fracture energy, friction energy, strain energy, and hysteresis loss were taken into consideration for the analysis of the different stages of needle insertion and extraction. The results demonstrated that (1) although the TM shows viscoelastic behavior, the contribution of hysteresis loss was negligible compared to other irreversible dissipated energy components (i.e., fracture energy and friction energy). (2) The TM puncture force did not substantially change during the first hours after animal death, but interestingly, it increased after 1 week due to the drying effects of soft tissue. (3) The needle geometry affected the crack length and the most important features of the force-displacement plot for the needle insertion process (puncture force, puncture displacement, and jump-in force) increased with increasing needle diameter, whereas the insertion velocity only changed the puncture and jump-in forces (both increased with increasing insertion velocity) and did not have a noticeable effect on the puncture displacement. (4) The fracture toughness of the gerbil TM was almost independent of the needle geometry and was found to be around 0.33 ± 0.10 kJ/m2.

Comparison between head rotation and standard techniques for i-gel™ insertion: a randomized controlled trial.

BACKGROUND: This study evaluated the effect of head rotation on the first-attempt success rate of i-gel insertion, aiming to alleviate the effect of gravity on the tongue and reduce resistance between the device and the tongue. METHODS: Adult surgical patients were randomized to standard and head rotation technique groups. In the head rotation technique group, patients' heads were maximally rotated to the left before i-gel insertion. The primary endpoint was the first-attempt success rate. Secondary endpoints included the success rate within two attempts (using the allocated technique), time required for successful i-gel placement within two attempts, and success rate at the third attempt (using the opposite technique). RESULTS: Among 158 patients, the head rotation technique group showed a significantly higher first-attempt success rate (60/80, 75.0%) compared to the standard technique group (45/78, 57.7%; P = 0.021). The success rate within two attempts was similar between the groups (95.0% vs. 91.0%, P = 0.326). The time required for successful i-gel placement was significantly shorter in the head rotation technique (mean [SD], 13.4 [3.7] s vs. 16.3 [7.8] s; P = 0.030). When the head rotation technique failed, the standard technique also failed in all cases (n = 4), whereas the head rotation technique succeeded in five out of the seven patients where the standard technique failed. CONCLUSIONS: The head rotation technique significantly improved the first-attempt success rate and reduced the time required for successful i-gel insertion. It was effective when the standard technique failed. The head rotation technique may be an effective primary or alternative method for i-gel insertion. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT05201339).

Incidence of medical adhesive-related skin injury: a reduction by changing posture.

OBJECTIVE: Medical adhesive-related skin injuries (MARSI), defined as skin damage associated with the use of medical adhesive products or devices, are a common and under-reported condition that compromises skin integrity. The prevention and management of MARSI that can occur around the needle insertion site of a chest wall implantable port in hospitalised patients with a tumour remain challenging issues. The aim of this study was to explore whether the incidence of MARSI could be reduced by changing the body position during dressing changes. METHOD: Participants were recruited between May 2019 and November 2020 in the oncology department of a tertiary hospital. Patients were randomly assigned to Group AB (supine followed by semi-recumbent position) and Group BA (semi-recumbent followed by supine position) with a standard intervening recovery interval of 21-28 days. Assessments for typical MARSI included itching, the combination of erythema and oedema, and blisters in the port area, and were graded according to the level of severity. RESULTS: The itch intensity was significantly lower in phase B (semi-recumbent) compared to phase A (supine) (2.35±1.985 versus 5.31±1.332, respectively; p<0.01). Similarly, the severity of erythema and oedema was less severe when comparing phase B to phase A: grade 0 (64.9% versus 10.5%, respectively); grade 1 (28.1% versus 19.3%, respectively); grade 2 (3.5% versus 7.0%, respectively); grade 3 (1.8% versus 45.6%, respectively); and grade 4 (1.8% versus 17.5%, respectively) (Z=5.703; p<0.01). Blisters were found far less frequently in phase B than phase A (1.8% versus 56.1%, respectively; p<0.01). CONCLUSION: The study provided statistically significant evidence that patients in a semi-recumbent position receiving dressing at a chest wall implantable port had fewer and less severe injection site MARSI than when in a supine position. DECLARATION OF INTEREST: The authors have no conflicts of interest to declare.

Unveiling novel genetic variants in 370 challenging medically relevant genes using the long read sequencing data of 41 samples from 19 global populations.

BACKGROUND: A large number of challenging medically relevant genes (CMRGs) are situated in complex or highly repetitive regions of the human genome, hindering comprehensive characterization of genetic variants using next-generation sequencing technologies. In this study, we employed long-read sequencing technology, extensively utilized in studying complex genomic regions, to characterize genetic alterations, including short variants (single nucleotide variants and short insertions and deletions) and copy number variations, in 370 CMRGs across 41 individuals from 19 global populations. RESULTS: Our analysis revealed high levels of genetic variants in CMRGs, with 68.73% exhibiting copy number variations and 65.20% containing short variants that may disrupt protein function across individuals. Such variants can influence pharmacogenomics, genetic disease susceptibility, and other clinical outcomes. We observed significant differences in CMRG variation across populations, with individuals of African ancestry harboring the highest number of copy number variants and short variants compared to samples from other continents. Notably, 15.79% to 33.96% of short variants were exclusively detectable through long-read sequencing. While the T2T-CHM13 reference genome significantly improved the assembly of CMRG regions, thereby facilitating variant detection in these regions, some regions still lacked resolution. CONCLUSION: Our results provide an important reference for future clinical and pharmacogenetic studies, highlighting the need for a comprehensive representation of global genetic diversity in the reference genome and improved variant calling techniques to fully resolve medically relevant genes.

Theoretical study on the insertion reaction of the stannylenoid H2SnLiF with X-H bonds (X = N, O, F).

The insertion reactions of p-complex (RP) and three-membered ring configuration (RS) of stannylenoid H2SnLiF with NH3, H2O and HF have been studied theoretically by quantum chemical calculation. The structures of reactants, precursors, transition states, intermediates and products have been fully optimized at the M06-2X/def2-TZVP level. The single point energy of all fixed points were calculated using the QCISD method. The calculation results show that the three-membered ring configuration is easier to conduct the insertion reaction. Comparing the reaction energy barriers of RP, RS to NH3, H2O and HF, we found that the difficulty of the insertion reaction is NH3 > H2O > HF. The solvent corrected calculation results show that in THF, the reaction energy barrier of RP is lower than that in vacuum, while the reaction energy barrier of RS is higher. This work provides theoretical support for the reaction properties of stannylenoid.

A prospective randomized controlled trial of water exchange plus cap versus water exchange colonoscopy in unsedated Veterans.

BACKGROUND AND AIMS: Water exchange (WE) and cap-assisted colonoscopy (CAC) separately reduced pain during insertion in unsedated patients. We hypothesized that compared with WE, WECAC could significantly lower real-time maximum insertion pain (RTMIP). METHODS: Veterans without escort were recruited, randomized, blinded, and examined at three United States Veterans Affairs sites. The primary outcome was RTMIP, highest segmental pain (0 = no pain, 10 = most severe pain) during insertion. RESULTS: Randomization [WECAC (n = 143) and WE (n = 137)] produced even distribution of a racially diverse group of males and females of low socioeconomic status. Intention-to-treat analysis reported results of WECAC (listed first) and WE (listed second): cecal intubation [93%, 94.2%]; mean (SD) of RTMIP [2.9 (2.5), 2.6 (2.4)]; the proportion with no pain (28.7%, 27.7%); the insertion time [18.6 (15.6), 18.8 (15.9) min]; overall ADR (55.2%, 62.8%), all P values were > 0.05. When RTMIP was binarized as "no pain" (0) vs. "some pain" (1-10), or "low pain" (0-7) vs. "high pain" (8-10), different significant predictors (see text) of RTMIP were identified. CONCLUSIONS: Unsedated colonoscopy was appropriate for unescorted Veterans. WE alone was sufficient. Adding a cap did not reduce RTMIP. Patient specific factors and application of WE with insertion suction of infused water contributed to high and low RTMIP, respectively. For unesorted patients, selecting those with low anxiety, avoiding low body mass index, history of depression or self-reported poor health and adhering to the steps of WE can minimize RTMIP to ensure success of unsedated colonoscopy.

Effect of Different Graft Material Consistencies in the Treatment of Minimal Bone Dehiscence: A Retrospective Pilot Study.

Among different therapeutic strategies proposed in the case of bone volume deficit, guided bone regeneration (GBR) is a consolidated surgical procedure. The objective of this study is to retrospectively evaluate the behavior of two bone grafts with different consistencies in the GBR procedure by measuring the volumetric tissue changes 1 year after surgery. For this retrospective analysis, 25 cases of GBR with simultaneous implant insertion were selected. A total of 13 were grafted with a porcine cortico-cancellous bone mix (CCBM group), and 12 were grafted with a pre-hydrated granulated cortico-cancellous bone mix of porcine origin blended with 20% TSV gel (Collagenated-CCBM). A collagen membrane was fixed to cover the bone defect. A total of 42 implants were placed with computer-guided surgery. Preoperative and 12-month postoperative digital impressions were used to evaluate dimensional changes. Student's t-test used for independent samples showed no statistically significant differences between the integrated distance (p = 0.995) and mean distance (p = 0.734). The mean integrated distance in the CCBM group was 41.80 (SD. 101.18) compared to a mean of 42.04 (SD. 66.71) in the Collagenated-CCBM group. Given the limitations of this study, in patients with peri-implant bone dehiscence, simple heterologous and collagenated heterologous cortico-cancellous bone grafts are suitable for filling the bone defect to promote bone regeneration, although further studies are needed.

Advancing Pain Management Protocols for Intrauterine Device Insertion: Integrating Evidence-Based Strategies Into Clinical Practice.

The discomfort and anxiety associated with the intrauterine device (IUD) insertion process is a significant barrier to its adoption as a form of contraception despite its high efficacy. This study aimed to classify and identify methods for minimizing pain and anxiety in IUD implantation in women below the age of 49. A search of publications from online databases, PubMed and Google Scholar, revealed 14 articles that met the inclusion criteria. An analysis of the selected studies showed that several pharmacological and non-pharmacological measures effectively minimized patient discomfort associated with IUD insertion. Of the 14 studies, 12 evaluated pharmacological methods for pain management in IUD insertion, while two studies assessed non-pharmacological methods. The results showed that although the IUD is more effective than other forms of contraceptives, fear of pain related to the insertion process is one of the most significant barriers to the use of an IUD among women. Most studies identified pharmacological methods of pain management for IUD insertion, highlighting a need for more research on non-pharmacological methods to improve patient experiences and reduce associated fears.

A Data-driven Approach for Enhanced CO2 Capture with Ruthenium Complexes.

To attain carbon neutrality, significant efforts have been made to capture and use CO2. The homogeneous hydrogenation of CO2 catalyzed by transition metal complexes, particularly ruthenium complexes, has demonstrated significant advantages and is regarded as a viable approach for practical application. Insertion of CO2 into the Ru-H bond, producing the Ru-formate product, is the key step in the hydrogenation of CO2. In order to parameterize the catalytic activities in the CO2 insertion into the Ru-H bond, the concept of simplified mechanism-based approach with data-driven practice (SMADP) has been introduced in this paper. The results showed that the hydricity of the Ru-H complex (ΔGH-) might serve as a single active descriptor in the process of CO2 insertion, and that a novel Ru complex in CO2 catalysis may not be easily obtained by mere modification of the auxiliary ligand at the ruthenium metal site.

Exploring ethylene insertion reaction mechanism in nickel complexes: a comparative study by the reaction force and reaction electronic flux in molecular and SiO2-supported catalysts.

CONTEXT: This study investigates the ethylene insertion reaction mechanism for polymerization catalysis, aiming to discern differences between Ni-α-imine ketone-type catalyst and their SiO2-supported counterpart. The reaction force analysis unveils a more intricate mechanism with SiO2 support, shedding light on unexplored factors and elucidating the observed lower catalytic activity. Furthermore, reactivity indexes suggest earlier ethylene activation in the supported catalyst, potentially enhancing overall selectivity. Finally, the reaction electronic flux analysis provides detailed insights into the electronic activity at each step of the reaction mechanism. In sum, this study offers a comprehensive understanding of the ethylene insertion reaction mechanism in both molecular and supported catalysts, underscoring the pivotal role of structural and electronic factors in catalytic processes. METHODS: Density functional theory (DFT) calculations were conducted using the ωB97XD functional and the 6-31 + G(d,p) basis sets with Gaussian16 software. Computational techniques utilized in this study encompassed the IRC method, reaction force analysis, and evaluation of electronic descriptors such as electronic chemical potential, molecular hardness, and electrophilicity reactivity indexes. Additionally, reaction electronic flux analysis was employed to investigate electronic activity along the reaction coordinate.