Phosphorescent metallaknots of Au(I)-bis(acetylide) strands directed by Cu(I) π-coordination.

Knots containing metal atoms as part of their continuous strand backbone are termed as metallaknots. While several metallaknots have been synthesized through one-pot self-assembly, the designed synthesis of metallaknots by controlling the arrangement of entanglements and strands connectivity remains unexplored. Here, we report the synthesis of metallaknots composed with Au(I)-bis(acetylide) linkages and templated by Cu(I) ions. Varying the ratio of the building blocks results in the switchable formation of two trefoil knots with different stoichiometries and symmetries (C2 or D3) and an entangled metalla-complex. While the entangled complex formed serendipitously, the strand ends can be subsequently linked through coordinative closure to generate a 41 metallaknot in a highly designable fashion. The comparable structural characteristics of resulting metalla-complexes allow us to probe the correlations between their topologies and photophysical properties, showing the backbone rigidity of knots endows complexes with excellent phosphorescent properties. This strategy, in conjunction with the coordinative closure approach, provides a straightforward route for the formation of highly phosphorescent metallaknots that were previously challenging to access.

Theta-curves in proteins.

We study and characterize the topology of connectivity circuits observed in natively folded protein structures whose coordinates are deposited in the Protein Data Bank (PDB). Polypeptide chains of some proteins naturally fold into unique knotted configurations. Another kind of nontrivial topology of polypeptide chains is observed when, in addition to covalent bonds connecting consecutive amino acids in polypeptide chains, one also considers disulfide and ionic bonds between non-consecutive amino acids. Bonds between non-consecutive amino acids introduce bifurcation points into connectivity circuits defined by bonds between consecutive and nonconsecutive amino acids in analyzed proteins. Circuits with bifurcation points can form θ-curves with various topologies. We catalog here the observed topologies of θ-curves passing through bridges between consecutive and non-consecutive amino acids in studied proteins.

Slow-exploring captive red knots were quicker to find food in a social setting than fast explorers.

Individuals foraging in groups face increased competition but can benefit from social information on foraging opportunities that can ultimately increase survival. Personality traits can be associated with food-finding strategies, such as shyer individuals scrounging on the food discoveries of others. How personality and foraging strategy interact in a social foraging context with different group compositions received less attention. Here, we conducted experiments to investigate the relationship between exploratory personality, group size (1-4 birds) and foraging success (i.e. speed of finding a food patch) in wild-caught red knots. We found that faster explorers, when foraging alone, discover food patches quicker than slower explorers. In groups, however, slower-exploring birds became quicker at finding food than fast explorers. This shows that slower-exploring individuals benefit from group foraging. They seem to be more perceptive to social cues, and in contrast to faster explorers, they become quicker at finding food when they are in a group than when foraging alone. We discuss how individuals with different personalities and foraging strategies can coexist in a social foraging context with different costs and benefits associated with their strategies.

Synergizing Steric Hindrance and Stacking Interactions To Facilitate the Controlled Assembly of Multiple 41 Metalla-Knots and Pseudo-Solomon Links.

In this work, a noncoplanar terphenyl served as a building block to synthesize a novel 3,3'-substituted bipyridyl ligand (L1) which further reacted with binuclear half-sandwich units A/B, giving rise to two aesthetic 41 metalla-knots in high yields via a coordination-driven self-assembly strategy. Furthermore, given the inherent compactness of the 41 metalla-knots, it creates favorable conditions for the emergence of steric repulsion. We focused on progressively introducing nitrogen atoms featuring a lone pair of electrons (LPEs) into ligand L1 to manipulate the balance of H⋅⋅⋅H/LPEs⋅⋅⋅LPEs steric repulsion during the assembly process, ultimately achieving controlled assembly from 41 metalla-knots to the pseudo-Solomon link and then to molecular tweezer-like assembly facilitated by stacking interactions. All the assemblies were well characterized by solution-state NMR techniques, ESI-TOF/MS, and single-crystal X-ray diffraction. The evolutionary process of the topological architectures is equivalent to visualizing the synergistic effect of steric hindrance and stacking interactions on structural assembly, providing a new avenue for achieving the controlled synthesis of different topologies.

The codriven assembly of molecular metalla-links ([Formula: see text], [Formula: see text]) and metalla-knots ([Formula: see text], [Formula: see text]) via coordination and noncovalent interactions.

Although mechanically interlocked molecules (MIMs) display unique properties and functions associated with their intricate connectivity, limited assembly strategies are available for their synthesis. Herein, we presented a synergistic assembly strategy based on coordination and noncovalent interactions (π-π stacking and CH⋯π interactions) to selectively synthesize molecular closed three-link chains ([Formula: see text] links), highly entangled figure-eight knots ([Formula: see text] knots), trefoil knot ([Formula: see text] knot), and Borromean ring ([Formula: see text] link). [Formula: see text] links can be created by the strategic assembly of nonlinear multicurved ligands incorporating a furan or phenyl group with the long binuclear half-sandwich organometallic Cp*RhIII (Cp* = η5-pentamethylcyclopentadienyl) clip. However, utilizing much shorter binuclear Cp*RhIII units for union with the 2,6-naphthyl-containing ligand led to a [Formula: see text] knot because of the increased π-π stacking interactions between four consecutive stacked layers and CH⋯π interactions. Weakening such π-π stacking interactions resulted in a [Formula: see text] knot. The universality of this synergistic assembly strategy for building [Formula: see text] knots was verified by utilizing a 1,5-naphthyl-containing ligand. Quantitative conversion between the [Formula: see text] knot and the simple macrocycle species was accomplished by adjusting the concentrations monitored by NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Furthermore, increasing the stiff π-conjugated area of the binuclear unit afforded molecular Borromean ring, and this topology is a topological isomer of the [Formula: see text] link. These artificial metalla-links and metalla-knots were confirmed by single-crystal X-ray diffraction, NMR and ESI-MS. The results offer a potent strategy for building higher-order MIMs and emphasize the critical role that noncovalent interactions play in creating sophisticated topologies.

Automated titanium fastener for surgical aortic valve replacement-preventive role for infective endocarditis?

OBJECTIVES: Evidence on long-term clinical outcomes considering suture-securing techniques used for surgical aortic valve replacement is still uncertain. METHODS: A total of 1405 patients who underwent surgical aortic valve replacement between January 2016 and December 2022 were included and grouped according to the suture-securing technique used (automated titanium fastener versus hand-tied knots). The occurrence of infective endocarditis during follow-up was set as the primary study end-point. As secondary study end-points, stroke, all-cause mortality and a composite outcome of either infective endocarditis, stroke, or all-cause mortality were assessed. RESULTS: The automated titanium fastener was used in 829 (59%) patients, whereas the hand-knot tying technique was used in 576 (41%) patients. The multivariable proportional competing risk regression analysis showed a significantly lower risk of infective endocarditis during follow-up in the automated titanium fastener group (adjusted sub-hazard ratio 0.44, 95% confidence interval 0.20-0.94, P = 0.035). The automated titanium fastener group was not associated with an increased risk of mortality or attaining the composite outcome, respectively (adjusted hazard ratio 0.81, 95% confidence interval 0.60-1.09, P = 0.169; adjusted hazard ratio 0.82, 95% confidence interval 0.63-1.07, P = 0.152). This group was not associated with an increased risk of stroke (adjusted sub-hazard ratio 0.82, 95% confidence interval 0.47-1.45, P = 0.504). Also, a significantly lower rate of early-onset infective endocarditis was observed in the automated titanium fastener group, (0.4% vs 1.4%, P = 0.032). CONCLUSIONS: Suture-securing with an automated titanium fastener device appears to be superior compared to the hand-knot tying technique in terms of lower risk of infective endocarditis.

Electrophoretic Mobility Assay to Separate Supercoiled, Catenated, and Knotted DNA Molecules.

Two-dimensional (2D) agarose gel electrophoresis is the method of choice to analyze DNA topology. The possibility to use E. coli strains with different genetic backgrounds in combination with nicking enzymes and different concentrations of norfloxacin improves the resolution of 2D gels to study the electrophoretic behavior of three different families of DNA topoisomers: supercoiled DNA molecules, post-replicative catenanes, and knotted DNA molecules. Here, we describe the materials and procedures required to optimize their separation by 2D gels. Understanding the differences in their electrophoretic behavior can help explain some important physical characteristics of these different types of DNA topoisomers. Key features • Preparative method to enrich DNA samples of supercoiled, catenated, and knotted families of topoisomers, later analyzed by 2D gels (or other techniques, e.g., microscopy). • 2D gels facilitate the separation of the topoisomers of any given circular DNA molecule. • Separation of DNA molecules with the same molecular masses but different shapes can be optimized by modifying the conditions of 2D gels. • Evaluating the roles of electric field and agarose concentration on the electrophoretic mobility of DNA topoisomers sheds light on their physical characteristics.

Alexander and Jones polynomials of weaving 3-braid links and Whitney rank polynomials of Lucas lattice.

In this paper, a connection is established between the Jones polynomial of generalized weaving knots of type W(3,n,m) and the Chebyshev polynomial of the first kind. Consequently, it is proved that the coefficients of the Jones polynomial of weaving knots are essentially the Whitney numbers of Lucas lattices. Additionally, an explicit formula for the coefficients of the Alexander polynomial of weaving knots W(3,n) is introduced, and it is proven that these coefficients satisfy Fox's trapezoidal conjecture.

Efficacy of automated fasteners versus hand-tied knots in cardiac surgery: a systematic review and meta-analysis.

Valve surgery is common in cardiac procedures, with fasteners like COR-KNOT® and hand-tied knots used for knot securing. This study compares their efficacy in valve surgery patients. We searched PubMed, SCOPUS, and Cochrane Central until August 2023. Outcomes assessed included aortic cross-clamp time (AXT), cardiopulmonary bypass (CPB) time, valvular regurgitation, mortality, prolonged ventilatory support, atrial fibrillation, postoperative left ventricular ejection fraction (LVEF), and renal failure. Subgroup analysis was performed for minimally invasive and open cardiac surgery. We used a random effects model for analysis. We included eight observational studies and two randomized controlled trials (RCTs) with a total of 1.411 participants. COR-KNOT significantly reduced AXT [MD -15.14, 95 % CI (-18.57, -11.70), P<0.00001] and CPB time [MD -12.38, 95 % CI (-14.99, -9.77), P<0.00001]. Valvular regurgitation [RR 0.40, 95 % CI (0.26, 0.61), P<0.0001] and need for prolonged ventilatory support [RR 0.29, 95 % CI (0.13, 0.65), P=0.003] were significantly lower with COR-KNOT. There were no significant differences in mortality [RR 0.39, 95 % CI (0.09, 1.69), P=0.44], atrial fibrillation [RR 1.03, 95 % CI (0.83, 1.27), P=0.81], LVEF changes [MD 0.05, 95 % CI (-1.37, 1.47), P = 0.95], or renal failure [RR 0.87, 95 % CI (0.16, 4.80), P = 0.87]. COR-KNOT devices reduce operative time and valvular regurgitation without increasing mortality or adverse outcomes. This supports their use in enhancing surgical efficiency and patient outcomes. However, ongoing discussions about suturing techniques, especially in minimally invasive procedures, highlight the need for further research and consensus among practitioners. See also the graphical abstract(Fig. 1).

Double true umbilical cord knots coexisting with a nuchal cord with successful fetal outcome: A case report.

Umbilical nodes and cords play a crucial role in fetal development and are essential for the transfer of nutrients and oxygen between the mother and the fetus. Sonographic diagnosis of umbilical nodes and cords has become an integral part of prenatal care, allowing for the early detection of abnormalities and potential complications. The umbilical cord is a vital structure connecting the fetus to the placenta, providing essential nutrients and oxygen for fetal growth and development. Sonographic examination of the umbilical cord and its associated nodes has become an indispensable tool in prenatal care, enabling the early detection of abnormalities and potential complications. This review aims to analyze the current literature on sonographic diagnosis of umbilical nodes and cords, highlighting the key points and advancements in this field. A 37-year-old booked G4P2+1A2 Nigerian woman was registered for prenatal tertiary health care at 12 weeks of gestation. The booking investigations were normal and the booking packed cell volume was 37%. She was compliant with scheduled clinic visits and routine drugs. Pregnancy was carried to term uneventfully. Elective cesarean section was successfully performed at 38 weeks of gestation owing to the patient's prior history of third-degree perineal tear. The intraoperative findings included a loose cord around the neck of the baby and double true knots along the length of the 65 cm umbilical cord. The baby was delivered with appearance, pulse, grimace, activity and respiration (APGAR) scores of 7 in the first minute, 9 in the fifth minute, and the birth weight was 3.0 kg. Mother and baby were discharged 48 h postpartum in stable clinical condition. Although the presence of true double umbilical knots is rare, its coexistence with the nuchal cord is even rarer. There are risk factors associated with true umbilical knots. The possible risk factor implicated in this index case is the gender of the fetus and maternal multiparity. True umbilical knots are usually associated with certain fetal negative outcomes of pregnancy. There are currently no evidence-based treatment options available.

One-Step Microfluidic Fabrication of Bioinspired Microfibers with a Spindle-Knot Structure for Fog Harvest.

Many biomimetic microfibers have been designed from spider silk to collect water efficiently from humid air as a result of its periodic spindle-knot structure, which enhances the direct movement and convergence of captured fog droplets. Here, a hydrodynamic flow-focusing microfluidic device with a theta-shaped tube is designed for the one-step fabrication of bioinspired microfibers with a spindle-knot structure for fog harvest. The morphology of the structured microfibers, including height, width, and spacing of spindle knots, can be adjusted readily by regulating the flow rate of specific phases. The production rate of these structured microfibers can reach 1100 cm/min. Moreover, the capture, transportation, and collection performance of fog droplets on various microfibers are investigated in a fog collection platform. It is demonstrated that our one-step microfluidic device presents a ready method for the fabrication of structured microfibers with spindle knots, which provide a significant facilitation on efficient fog capture and water collection.

Automated titanium fastener vs. hand-tied knots for prosthesis fixation in infective endocarditis.

Objectives: To date, there is no evidence regarding the safety of automated titanium fastener compared with hand-tied knots for prosthesis fixation in infective endocarditis. Methods: Between January 2016 and December 2022, a total of 220 patients requiring surgery for infective endocarditis were included in this retrospective analysis. The primary study endpoint was re-endocarditis during follow-up. The secondary study endpoints included stroke onset, all-cause mortality, and a composite outcome of either re-endocarditis, stroke, or all-cause mortality during follow-up. Results: Suture-securing with an automated titanium fastener was performed in 114 (51.8%) patients, whereas the conventional technique of hand knot-tying was used in 106 (48.2%) patients. The risk of re-endocarditis was significantly lower in the automated titanium fastener group, as shown in a multivariable proportional competing risk regression model (adjusted sub-hazard ratio 0.33, 95% confidence interval 0.11-0.99, p = 0.048). The multivariable Cox proportional hazards regression analysis showed that the automated titanium fastener group was not associated with an increased risk of stroke-onset or attaining the composite outcome, respectively, (adjusted hazard ratio 0.54, 95% confidence interval 0.27-1.08, p = 0.082), (adjusted hazard ratio 0.65, 95% confidence interval 0.42-1.02, p = 0.061). Also, this group was not associated with an increased risk of all-cause mortality, as demonstrated in the multivariable Poisson regression analysis (adjusted incidence-rate ratio 1.42, 95% confidence interval 0.83-2.42, p = 0.202). Conclusions: The use of automated titanium fastener device seems to be safe for infective endocarditis. Analyses of larger cohorts are required.

Intracorporeal vs. extracorporeal open and closed knot tying techniques in laparoscopy: A randomized, controlled study.

Objective: Tying knots during suturing is one of the most challenging tasks in laparoscopic surgery. Therefore, measures aimed at ensuring both the ease and speed of knot tying not only benefit the surgeon but can also reduce operating time significantly. This study compared extracorporeal and intracorporeal knot tying techniques using a Szabo pelvic trainer model from the Gynaecological Endoscopic Surgical Education and Assessment program. Design: The students tied intra- and extracorporeal knots using closed- and open-jaw knot pushers. Using an artificial tissue suturing pad in a certified Szabo pelvic trainer, students tied three knots using each technique according to block randomization. Task completion time, knot strength, knot-spread ability, and number of errors were recorded. The Wilcoxon test and mixed-effects models were used to analyze the results. After completing the exercises, participants answered a questionnaire concerning knot-tying techniques and their performance. Setting: University Hospital Basel, which provides tertiary-level clinical care. Participants: Fifty-seven medical students with no experience in laparoscopy voluntarily signed up for this study. Results: Open and closed extracorporeal knot tying was significantly faster (p < 0.001, p < 0.001, respectively), more precise (p = 0.007, p = 0.003), and associated with reduced knot-spread ability (p < 0.001, p < 0.001) compared to intracorporeal knot tying. Open- and closed-jaw knot pushers were shown to be equal in terms of speed (p = 0.563), knot-spread ability (p = 0.49), and precision (p = 0.831). The study participants rated open (30 %) and closed (49 %) extracorporeal knot tying as more intuitive than intracorporeal (21 %) knot tying. Improved concentration was significantly correlated with tighter knots (p = 0.011). Conclusions: Students achieved significantly better results using extracorporeal knot-tying techniques than intracorporeal ones, including greater speed, tighter knots, and optimized precision. These results suggest that beginners in the field of laparoscopy should be encouraged to practice extracorporeal knot-tying techniques.

Unidirectional barbed sutures vs. interrupted intracorporeal knots in thoracoscopic repair of congenital diaphragmatic hernia in pediatrics.

Background: Intracorporeal suturing knots continue to be one of the most challenging and time-consuming steps in the thoracoscopic repair of congenital diaphragmatic hernia (CDH). Barbed unidirectional knotless sutures are designed to shorten surgical procedures by eliminating the need to tie knots. This work aimed to compare unidirectional barbed sutures and interrupted intracorporeal knots in the thoracoscopic repair of CDH in pediatrics regarding the time required to suture, operative time and complications. Methods: This retrospective study included 139 patients presented with Bochdalek CDH. Patients were classified into early (neonatal) and late presentations. The hernia defect was repaired by unidirectional Barbed sutures (V-LocTM and StratafixTM sutures) in group B or by Conventional interrupted intracorporeal knots in group C. Results: In both early and delayed presentations, the time required to suture (15 and 13 min in group B, 33 and 28 min in group C for neonatal and delayed presentation respectively) was significantly shorter in group B. Complications (visceral perforation, wound infection, and recurrence) insignificantly differed between group B and group C of early presentation. No patients suffered from major complications in both groups. Conclusions: Both unidirectional barbed sutures and intracorporeal knots were safe and effective. However, unidirectional barbed sutures are a time-saving choices for CDH thoracoscopic repair in early and late presentations.

Comparison of different suture techniques for laparoscopic vaginal cuff closure.

Laparoscopic hysterectomy is a commonly performed procedure. However, one high-risk complication is vaginal cuff dehiscence. Currently, there is no standardization regarding thread material or suturing technique for vaginal cuff closure. Therefore, this study aimed to compare extracorporeal and intracorporeal suturing techniques for vaginal cuff closure using a pelvic trainer model. Eighteen experts in laparoscopic surgery performed vaginal cuff closures with interrupted sutures using intracorporeal knotting, extracorporeal knotting and continuous, unidirectional barbed sutures. While using an artificial tissue suturing pad in a pelvic trainer, experts performed vaginal cuff closure using each technique according to block randomization. Task completion time, tension resistance, and the number of errors were recorded. After completing the exercises, participants answered a questionnaire concerning the suturing techniques and their performance. Experts completed suturing more quickly (p < 0.001, p < 0.001, respectively) and with improved tension resistance (p < 0.001, p < 0.001) when using barbed suturing compared to intracorporeal and extracorporeal knotting. Furthermore, the intracorporeal knotting technique was performed faster (p = 0.04) and achieved greater tension resistance (p = 0.023) compared to extracorporeal knotting. The number of laparoscopic surgeries performed per year was positively correlated with vaginal cuff closure duration (p = 0.007). Barbed suturing was a time-saving technique with improved tension resistance for vaginal cuff closure.

Non-hypertensive gestational diabetes mellitus: Placental histomorphology and its association with perinatal outcomes.

INTRODUCTION: Gestational diabetes mellitus (GDM) exerts a great impact on the placenta and reflects changes on placentas both morphological and functionally. The aims of this study are to evaluate the prevalence of placental histopathological lesions in pregnancies complicated by GDM compared to gestational age-matched controls, and their association with maternal and fetal complications. METHODS: Fifty-four singleton GDM-complicated pregnancies were recruited and compared to 33 consecutive normal pregnancies. Two pathologists, blinded to all clinical data, reviewed and evaluated all histological samples of the placentas in accordance with Amsterdam criteria. Relevant demographic, clinical data and primary birth outcomes were recorded. RESULTS: A myriad of histomorphological abnormalities, including chronic inflammation (n = 9/54, p = 0.031), histological chorioamnionitis (n = 23/54, p < 0.001), umbilical/chorionic vasculitis (n = 9/54, p = 0.031), changes related to maternal vascular malperfusion (n = 22/54, p = 0.003), chorangiosis (n = 10/54, p = 0.046) and villous dysmaturity (n = 9/54, p = 0.012) were observed more frequently in the GDM placentas compared to the controls. Additionally, GDM significantly increased the risk of fetal complications, including macrosomia/fetal growth restriction (n = 13/54, p = 0.004). DISCUSSION: Histoarchitectural abnormalities were observed more frequently in placentas of GDM pregnancies compared to the controls. Our findings support the hypothesis that diabetic-induced damage in the placental function may be associated with the increased in fetal growth disorders in GDM-complicated pregnancies.

Equity-related 'knots' in theory of change development: Conceptualization and case illustrations.

Theory of change (ToC) is an approach widely used to guide planning, implementing, and evaluating change initiatives. While there is substantial guidance, there has been little attention on equity within ToC research and practice. We propose and illustrate the metaphor of 'knots' to frame practical and ethical challenges that arise when centering equity within ToC processes. Drawing on our experiences using a ToC approach in two case examples, we identify and illustrate five equity-related knots: (a) clarify root causes, pathways, and success; (b) facilitate participation across power and perspective differences; (c) integrate research evidence and practitioner knowledge; (d) represent complex change visually; and (e) creatively navigate constraints. We show why framing these as knots can help practitioners make wise judgments within the circumstances and close with recommendations for including knots in ToC processes, reporting, and guidance.

Iminopyrrole-Based Self-Assembly: A Route to Intrinsically Flexible Molecular Links and Knots.

The use of 2,5-diformylpyrrole in self-assembly reactions with diamines and Zn(II)/Cd(II) salts allowed the preparation of [2]catenane, trefoil knot, and Borromean rings. The intrinsically dynamic nature of the diiminopyrrole motif rendered all of the formed assemblies intramolecularly flexible. The presence of diiminopyrrole revealed new coordination motifs and influenced the host-guest chemistry of the systems, as illustrated by hexafluorophosphate encapsulation by Borromean rings.

Cytology Techniques Can Provide Insight into Human Placental Structure Including Syncytiotrophoblast Nuclear Spatial Organisation.

The aim of this study was to provide the first systematic description of human placental cytology appearances and to investigate syncytiotrophoblast nuclear organisation patterns using cytology techniques. Term placentas from normal pregnancies were sampled using fine-needle aspiration (FNA) and direct scrapes. Standard histological examination was also performed to exclude pathological changes in the placentas being studied. Both Papanicolaou-stained cytospin preparations and air-dried Giemsa slides from FNA provided high-quality material for cytological assessment with good cellularity. Among the key features of the cytology preparations were villous "microbiopsies" that allowed for the three-dimensional appreciation of villous branching patterns. Cytological appearances, including nuclear characteristics of villous cytotrophoblast and syncytiotrophoblast, were also well demonstrated. In microbiopsies and detached villous trophoblast sheets, complex patterns of syncytiotrophoblast nuclear organisation, not previously described cytologically, were observed, including irregular spacing of nuclei, syncytioplasm windows and linear nuclear arrangements. This study showed that placental cytology (a) provides technically excellent material for cytological evaluation, (b) confirms the presence of complex nuclear organisational patterns in the syncytiotrophoblast by eliminating the possibility of tangential sectioning artefact, (c) provides superior nuclear detail over standard histological sections and (d) may be an untapped research resource for the investigation of normal and pathological processes because of its ability to look at the placenta in a novel way and through its potential for both ex vivo and in vivo placental sampling.