Complex Fragments Research Articles

The Golgi complex: An organelle that determines urothelial cell biology in health and disease

The Golgi complex undergoes considerable structural remodeling during differentiation of urothelial cells in vivo and in vitro. It is known that in a healthy bladder the differentiation from the basal to the superficial cell layer leads to the formation of the tightest barrier in our body, i.e., the blood–urine barrier. In this process, urothelial cells start expressing tight junctional proteins, apical membrane lipids, surface glycans, and integral membrane proteins, the uroplakins (UPs). The latter are the most abundant membrane proteins in the apical plasma membrane of differentiated superficial urothelial cells (UCs) and, in addition to well-developed tight junctions, contribute to the permeability barrier by their structural organization and by hindering endocytosis from the apical plasma membrane. By studying the transport of UPs, we were able to demonstrate their differentiation-dependent effect on the Golgi architecture. Although fragmentation of the Golgi complex is known to be associated with mitosis and apoptosis, we found that the process of Golgi fragmentation is required for delivery of certain specific urothelial differentiation cargoes to the plasma membrane as well as for cell–cell communication. In this review, we will discuss the currently known contribution of the Golgi complex to the formation of the blood–urine barrier in normal UCs and how it may be involved in the loss of the blood–urine barrier in cancer. Some open questions related to the Golgi complex in the urothelium will be highlighted.

Structural insights into the function-modulating effects of nanobody binding to the integrin receptor αMβ2

The integrin receptor αMβ2 mediates phagocytosis of complement-opsonized objects, adhesion to the extracellular matrix, and transendothelial migration of leukocytes. However, the mechanistic aspects of αMβ2 signaling upon ligand binding are unclear. Here, we present the first atomic structure of the human αMβ2 headpiece fragment in complex with the nanobody (Nb) hCD11bNb1 at a resolution of 3.2 Å. We show that the receptor headpiece adopts the closed conformation expected to exhibit low ligand affinity. The crystal structure indicates that in the R77H αM variant, associated with systemic lupus erythematosus, the modified allosteric relationship between ligand binding and integrin outside–inside signaling is due to subtle conformational effects transmitted over a distance of 40 Å. Furthermore, we found the Nb binds to the αI domain of the αM subunit in an Mg2+-independent manner with low nanomolar affinity. Biochemical and biophysical experiments with purified proteins demonstrated that the Nb acts as a competitive inhibitor through steric hindrance exerted on the thioester domain of complement component iC3b attempting to bind the αM subunit. Surprisingly, we show that the Nb stimulates the interaction of cell-bound αMβ2 with iC3b, suggesting that it may represent a novel high-affinity proteinaceous αMβ2-specific agonist. Taken together, our data suggest that the iC3b–αMβ2 complex may be more dynamic than predicted from the crystal structure of the core complex. We propose a model based on the conformational spectrum of the receptor to reconcile these observations regarding the functional consequences of hCD11bNb1 binding to αMβ2.

Abstract 570: Developing a novel adaptor CAR-T cell platform based on the recognition of the P329G Fc mutation in therapeutic IgG1 antibodies for adoptive T cell therapy

Abstract Chimeric antigen receptor (CAR) T cells have shown promising results for the treatment of blood cancers and various CAR-T cell approaches are in development for use in different tumor indications. Universal or modular CARs do not directly recognize the tumor target antigen, but bind via an adaptor molecule to their respective tumor target. We describe the P329G-CAR-T platform as a novel modular CAR-T cell platform that recognizes the P329G mutation in the Fc portion of IgG1 antibodies, a mutation frequently applied to abolish the Fc immune effector function of therapeutic antibodies. In contrast to other adaptor CAR-T cell platforms this approach does not rely on haptens or artificial tags fused to the targeting antibody.The crystal structure analysis of the anti-P329G Fab fragment in complex with a P329G-Fc portion showed that the Fab fragment recognizes the Fc mutation with 1:1 binding stoichiometry. Surface plasmon resonance analysis determined the equilibrium binding affinity of the P329G antibody to the P329G Fc-portion to be 15 nM. Cell assays using Jurkat-NFAT reporter cell lines and primary T cells transduced with the P329G-CAR showed specific recruitment of P329G CAR-T cells by P329G-containing antibodies, and potent and dose dependent tumor cell killing accompanied by IFNg release and subsequent T cell activation for several unrelated tumor antigens including CD20, CD33, HER2, FOLR1 and mesothelin. Notably, P329G-CAR-T cell killing activity was comparable to the activity of the respective direct scFv-based CAR-T cells, both in terms of kinetics and absolute killing potency. Finally, comparable activity was determined in comparison to CD16 extracellular domain (ECD)-based CAR-T cells engaging the CAR-T cells via the Fc-CD16-ECD interaction. In summary, P329G-CAR-T cells mediate potent tumor cell killing in combination with various tumor targeting antibodies as adaptor molecules. The combination with tumor targeting antibodies enables control of CAR-T activity by adjusting the dose and schedule of the respective antibody adaptor molecule. Importantly, different from CD16-ECD-based CAR-T cells, P329G-CAR-T cells cannot be engaged by endogenous immunoglobulins. In vivo studies to investigate efficacy and safety of P329G CAR-T cells are currently being completed and will be reported. Citation Format: Diana Darowski, Mohamed-Reda Benmebarek, Christian Jost, Kay Stubenrauch, Uwe Wessels, Joerg Benz, Anne Freimoser-Grundschober, Ekkehard Moessner, Pablo Umana, Sebastian Kobold, Christian Klein. Developing a novel adaptor CAR-T cell platform based on the recognition of the P329G Fc mutation in therapeutic IgG1 antibodies for adoptive T cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 570.

Endo-Aesthetic rehabilitation of complicated crown-root fracture of maxillary lateral incisor by fragment reattachment: A case report

In case of traumatic injuries to the anterior teeth, fragment reattachment is considered a minimally invasive technique. Re-attaching the same tooth fragment, possesses the advantage, of biomimicry by complete restoration of form, function, texture, lustre, and translucency. Due to advancements in adhesive dentistry, simple re-attachment to complex fragment rehabilitation have become predictable and reliable. Various techniques have been proposed for fragment reattachment based on the extent of injury, type of injury, condition of the fragment, and time- lapse. This case report demonstrates the endo-aesthetic rehabilitation of a complicated crown root fracture using a fiber post on lateral incisor with fracture line on the cervical 1/3of the labial aspect, running obliquely and apically towards the palatal surface after 1 year follow-up.

Stereoselective Synthesis of a Tetrasaccharide Fragment from Rhamnogalacturonan II Side Chain A

Comprehensive SummaryAn efficient synthesis of a complex tetrasaccharide fragment 1 structurally related to rhamnogalacturonan II side chain A has been accomplished through a stepwise glycosylation strategy. Challenges involved in the synthesis include the facile construction of the sterically crowded l‐fucopyranose core and the stereoselective formation of two 1,2‐cis‐glycosidic linkages. The 3,4‐disubstituted l‐fucopyranoside structure was successfully constructed through a ‘counterclockwise’ glycosylation sequence, namely, the less reactive axial 4‐OH group of the central fucose unit was glycosylated first, then the 3‐OH. Besides, a 2‐pyridinecarbonyl‐assisted α‐d‐xylosylation was developed to synthesize the α‐d‐xylopyranosidic linkage and a 3,4‐O‐benzoyl‐controlled α‐l‐galactosylation reaction was used for the stereoselective synthesis of the corresponding α‐l‐galactopyranosidic linkage.

Coagulation Response and Prothrombotic Effect of Uninterrupted Oral Anticoagulant Administration AfterCatheter Ablation for VT.

Catheter ablation for ventricular tachycardia (VT) is associated with perioperative thromboembolic risk. However, the strategy for postprocedural management remains unknown. The aim of this study was to evaluate the prothrombotic response after VT ablation in various coagulation biomarkers in patients with and without the administration of oral anticoagulation (OAC). Data from 112 patients (58 with uninterrupted OAC and 54 without) with structural heart disease who underwent endocardial VT ablation were retrospectively analyzed. We also included 41 patients who underwent ablation for premature ventricular contraction from the right ventricle and 13 patients who underwent electrophysiology study (the control group). Blood samples of coagulation markers were collected before and 3days after the procedure in all patients. The percentage of D-dimer levels≤1.0μg/mL at baseline was lower in the VT ablation groups (76% and 50% in the OAC and non-OAC groups, respectively) than in the other groups (100%). After 3days, the percentage remained at 67% in the OAC group; however, the non-OAC VT group demonstrated a remarkable decrease of 20%. Similarly, fibrin monomer complex, thrombin antithrombin, and prothrombin fragment 1+2 levels were well suppressed in the control, premature ventricular contraction, and OAC groups. However, the non-OAC group demonstrated increased coagulation markers both before and after 3days. Multivariate analysis demonstrated that OAC administration and normal coagulation markers at baseline were independent predictors of stable coagulation status after ablation. The coagulation cascade was significantly activated in patients undergoing VT ablation. Uninterrupted OAC administration suppressed the coagulation response, which might be associated with a reduction in perioperative prothrombotic risk.

QRS fragmentation and prolongation as predictors of exercise capacity in patients after Fontan palliation.

Patients with Fontan anatomy are at increased risk for exercise intolerance and early morbidity and mortality. QRS complex fragmentation (fQRS) and prolongation have been studied in multiple heart diseases, but their clinical importance is unknown in the Fontan population. A retrospective cross-sectional study was performed. ECGs were evaluated for QRS prolongation (>98 percentile for age) and fQRS (≥3 R-waves/notches in the R/S complex [more than two in RBBB] in ≥2 contiguous leads). The primary outcome measures were CPET performance. Total 90 patients (median age 18 years, 57% male, 59% RV dominant) were included; 13% had fQRS and 31% had prolonged QRS. Demographically, patients with fQRS or prolonged QRS were like those without. Peak VO2 (64% vs. 63%, p .45), VE/VCO2 slope (85% vs. 88%, p = .74), and O2 pulse (149% vs. 129%, p = .83) were similar in the fQRS group versus those without. Upon multi-variable regression, body mass index (β = -0.38, p < .01) and QRS duration (β = -0.29, p < .01) were independently associated with % predicted VO2; fQRS was not. Lower cardiac index (2.2 vs. 2.8 L/min/m2 , p = .03) and higher ventricular end-diastolic pressure (13 vs. 10 mmHg, p = .02) was seen with fQRS. QRS fragmentation is present in patients with Fontan physiology. fQRS showed no association with CPET performance but was related to invasive hemodynamic markers of ventricular performance. QRS duration may be a better predictor of exercise function following Fontan.

A multiview-based automatic method for 3D fracture line extraction

The 3D fracture line is the centerline of the crack region on the surface of the bone that can effectively help orthopedists understand fracture distribution and aid in fracture treatment. However, no effective automatic extraction method exists, and fracture lines still require manual work. This paper develops an efficient automatic method for fracture line extraction from multiple reassembled fragments. In the initial step, we propose a multiview sampling strategy based on spherical uniform viewpoints, which uses off-screen rendering to sample fragments from multiple viewpoints. Markers are generated from the samples and integrated from all viewpoints. Then, we use a new point-based centerline extraction algorithm to merge markers and extract the fracture lines. Finally, we propose a normal-based fracture line mapping method to quickly and reliably map fracture lines to the surface of a standard bone template. Experiments indicate that our method can extract fracture lines from six common complex fragments within 3 s. Through multiview experiments, we select 30 viewpoints so that most template mesh triangles corresponding to the six fragments can be simultaneously observed from at least 2 viewpoints. Additionally, anti-noise experiments show that the proposed method can handle high-noise and cancellous fragments reliably. For complex fragments, our method is still applicable, has strong practicality, and can effectively help doctors save time.

Transcriptomic Profiling Reveals Mesolimbic Gene Targets Associated with Oxycodone‐Seeking During Abstinence

AimsOver three million Americans suffer from opioid use disorder (OUD), a debilitating neurobiological disease characterized by dysfunctional physical and cognitive states. Despite success for medication‐assisted treatment, 50% of OUD patients exhibit recurring relapse episodes, emphasizing the need to identify novel drug targets to reduce recidivism rates. Individuals seeking to maintain abstinence from opioids are challenged by environmental context(s) and stimuli associated with previous drug use (e.g., paraphernalia). Cellular adaptations within the mesolimbic dopaminergic pathway from the ventral tegmental area (VTA) to the nucleus accumbens (NAc) are important in driving sensitivity to drug‐associated cues and relapse to drug consumption. The present study was designed to identify distinctions within the VTA and NAc transcriptomic landscape that associate with cue‐evoked oxycodone‐seeking during abstinence to identify novel gene targets for future OUD medications development.MethodsMale, Sprague‐Dawley rats were trained to stably self‐administer oxycodone (0.1 mg/kg/infusion) or saline (n=12/group) and underwent 10 days of abstinence prior to quantification of lever presses for cues previously associated with either oxycodone or saline self‐administration. Immediately following the test session, the VTA and NAc were isolated, and mRNA was processed for poly‐A tail transcriptomic profiling. We employed Poly(A)‐ClickSeq for generating RNAseq libraries adapted to direct the cDNA synthesis specifically toward the 3΄UTR/poly(A) tail junction of cellular RNA. This assay allows sensitive and specific enrichment for poly(A) site junctions without the need for complex sample preparation, fragmentation, or purification. The simple, scalable procedure generates high‐quality RNA‐Seq poly(A) libraries to identify and characterize the frequency and positions of poly(A) sites within the transcriptome. Genes that exhibited a false discovery rate (FDR)‐adjusted p&lt; 0.1 and a fold change ≥ ±1.5 were considered differentially expressed. Ingenuity Pathway Analysis (IPA) was used to identify neurobiological signatures within the VTA and NAc that associate with drug‐seeking during abstinence from oxycodone vs. self‐administration.ResultsAbstinence from oxycodone vs. saline self‐administration associated with a registry of 9,561 candidate gene targets in the VTA, but only 96 candidates in the NAc. IPA analysis identified differentially expressed genes in several biological pathways. Axonal guidance signaling was highly represented in the VTA, and synapse formation pathways were highly represented in the NAc. Excitingly, of the 261 genes represented in the opioid signaling pathway, 29 were differentially expressed in the VTA and eight were differentially expressed in the NAc following abstinence from oxycodone relative to saline self‐administration.ConclusionThe results of the present study identified unique differences in the transcriptomic landscape of key nodes in the mesolimbic circuitry following abstinence from saline or oxycodone self‐administration. In addition, the shared differentially expressed genes within the opioid signaling pathway (i.e., GNAS) provide prioritized candidates for future pharmacotherapeutics aimed to help maintain abstinence from oxycodone and prevent relapse in OUD.

Signature of fusion suppression in complex fragment emission

The effect of weak binding of $^{9}\mathrm{Be}$ on complete fusion has been explored through the study of complex fragment emission in $^{20}\mathrm{Ne}+^{9}\mathrm{Be}$ reaction. The yields of the fragments $^{6,7}\mathrm{Li}$ and $^{7,9}\mathrm{Be}$ emitted from the excited compound nucleus $^{29}\mathrm{Si}^{*}$ have been compared with the respective statistical model predictions. Emission of same fragments from another close-by compound nucleus $^{28}\mathrm{Si}^{*}$ at similar excitation energy, formed by the fusion of two strongly bound nuclei, $^{16}\mathrm{O}+^{12}\mathrm{C}$, has been studied for comparison. It has been observed that for the system $^{16}\mathrm{O}+^{12}\mathrm{C}$, the yields of $^{6,7}\mathrm{Li}$ and $^{7,9}\mathrm{Be}$ fragments are close to the predictions of the statistical model. However, for the $^{20}\mathrm{Ne}+^{9}\mathrm{Be}$ system, although the experimental yield pattern follows the statistical model prediction, there is substantial reduction in yield for all detected fragments. These observations have been attributed to the suppression of complete fusion in $^{20}\mathrm{Ne}+^{9}\mathrm{Be}$ system due to the weak binding of $^{9}\mathrm{Be}$, a dynamical effect which is not incorporated in the conventional statistical models. It is the first time that a clear signature of the suppression of complete fusion in light systems involving weakly bound nucleus has been observed in complex fragment emission from fully equilibrated composite produced in fusion well above the barrier.

A mesoscale study of micro-spallation of Cu through coarse-grained molecular dynamics modeling

Micro-spallation in metals is a complex dynamic fragmentation process accompanied by shock-induced overheating and melting. However, the damage evolution involved in this process, as well as the underlying mechanism, remain poorly understood. Here, a computationally efficient coarse-grained molecular dynamics (CGMD) method is used to study the micro-spallation of Cu. We demonstrate the capability of this method to reproduce results obtained by the classical molecular dynamics (MD) method in predicting spall damage of solid Cu under shock loading. CGMD simulations, however, give a higher spall strength and a later nucleation time compared with MD simulations, owing to the higher stress required to create collective voids in the former compared with the smaller individual voids in the latter. By contrast, the calculated values (including those of the compressive pressure, strain rate, and spall strength) and the predictions of microstructural evolution during micro-spallation of Cu obtained from CGMD simulations are in good agreement with those from MD simulations. This is attributed to the temperature immediately before spallation being sufficiently high for a strong shock to exist with a dominant effect on spallation, such that the collective motion of voids in CGMD simulations has a negligible effect on spall strength. A dependence of the spall strength on the strain rate of liquid Cu is proposed. This CGMD method allows the investigation of micro-spallation of Cu at the mesoscale.

Structural studies of fibrinolysis: how to disassemble a clot

Fibrin is degraded by the fibrinolytic system wich a plasminogen activator converts plasminogen to plasmin, a serine protease that cleaves specific bonds in fibrin leading to solubilization. To elucidate the biophysical processes involved in conversion of insoluble fibers to soluble fragments, fibrin was treared with either plasmin or the combination of plasminogen and its activator, and morphologic changes were observed using scanning electron microscopy. Initial changes in the fibrin matrix included creation of many free fiber ends and gaps in the continuity of fibers. With more extensive digestion, free fiber segments associated laterally, resulting in formation of thick fiber handles. Supernatants of digesting clots, containing soluble derivatives, were negatively contrasted and examined by transmission electron microscopy large complex fragments containing portions of multiple fibers were observed, as were piaces of individual fibers and smaller fragments. Some large fragments had sharply defined ends, indicating that they had been cleaved perpendicularly to the fiber direction. Other fibers showed splayed ends or a lacy meshwork of surrounding protofibrils. Fibrinolysis was also followed by confocal microscopy of plasma clots labeled with colloidal gold, so that changes at the lysis front of hydrated clots could be examined in real time. Clots made up of thin fibers were cleaved more slowly than clots made up of thick fibers, even though individual thin fibers were cleaved more rapidly. These results indicate that fibrinolytic degradation results in larger pieces than previously identified, and that plasmin digestion proceeds locally by transverse cutting across fibers rather than by progressive cleavage uniformly around the fiber. A model is proposed for the crawling of plasmin across fibrin fibers.

Therapeutic Strategies for Disseminated Intravascular Coagulation Associated with Aortic Aneurysm.

Aortic aneurysms are sometimes associated with enhanced-fibrinolytic-type disseminated intravascular coagulation (DIC). In enhanced-fibrinolytic-type DIC, both coagulation and fibrinolysis are markedly activated. Typical cases show decreased platelet counts and fibrinogen levels, increased concentrations of fibrin/fibrinogen degradation products (FDP) and D-dimer, and increased FDP/D-dimer ratios. Thrombin-antithrombin complex or prothrombin fragment 1 + 2, as markers of coagulation activation, and plasmin-α2 plasmin inhibitor complex, a marker of fibrinolytic activation, are all markedly increased. Prolongation of prothrombin time (PT) is not so obvious, and the activated partial thromboplastin time (APTT) is rather shortened in some cases. As a result, DIC can be neither diagnosed nor excluded based on PT and APTT alone. Many of the factors involved in coagulation and fibrinolysis activation are serine proteases. Treatment of enhanced-fibrinolytic-type DIC requires consideration of how to control the function of these serine proteases. The cornerstone of DIC treatment is treatment of the underlying pathology. However, in some cases surgery is either not possible or exacerbates the DIC associated with aortic aneurysm. In such cases, pharmacotherapy becomes even more important. Unfractionated heparin, other heparins, synthetic protease inhibitors, recombinant thrombomodulin, and direct oral anticoagulants (DOACs) are agents that inhibit serine proteases, and all are effective against DIC. Inhibition of activated coagulation factors by anticoagulants is key to the treatment of DIC. Among them, DOACs can be taken orally and is useful for outpatient treatment. Combination therapy of heparin and nafamostat allows fine-adjustment of anticoagulant and antifibrinolytic effects. While warfarin is an anticoagulant, this agent is ineffective in the treatment of DIC because it inhibits the production of coagulation factors as substrates without inhibiting activated coagulation factors. In addition, monotherapy using tranexamic acid in cases of enhanced-fibrinolytic-type DIC may induce fatal thrombosis. If tranexamic acid is needed for DIC, combination with anticoagulant therapy is of critical importance.

Qrs-Complex Fragmentations and Right Ventricular Infarction in the Presence of Inferior Infarction with Triple-Vessels Disease; Bad Initials but a Good Outcome

Rationale: The term “fragmentation of the QRS complex” denotes the existence of high-frequency potentials (spikes) in the QRS-complex. It is either a marker for cardiac structural diseases inducing biventricular hypertrophy or any condition interfering with the normally homogeneous depolarization status inside the myocardium. An associated right ventricular infarction with inferior infarction maybe carry a risk impact and serious complications. Patient concerns: A 64-year-old married, farmer, heavy smoker, Egyptian male patient presented with acute severe chest pain and inferior with right ventricular ST-segment elevation myocardial infarction and fragmentation of the QRS complex. Diagnosis: QRS-complex fragmentations and right ventricular infarction in the presence of inferior infarction with the triple-vessels disease. Interventions: Electrocardiography, oxygenation, streptokinase intravenous infusion, echocardiography, and percutaneous transluminal coronary angioplasty. Outcomes: Dramatic response of acute inferior with right ventricular ST-segment elevation myocardial infarction and QRS-complex fragmentations to streptokinase. Lessons: Despite the presence of inferior and right ventricular ST-segment elevation myocardial infarction with QRS-complex fragmentations, but there is no correlation with the severity of the disease. Dramatic clinical and electrocardiographic response signifying the role of streptokinase and fibrinolytic. The presence of fragmentation of the QRS-complex may have a bidirectional impact from seriousness to complications.

Gold(I) complexes of tetra-tert-butylcyclotetraphosphane.

The reaction of tetra-tert-butylcyclotetraphosphane cyclo-(PtBu)4 (L) with one to four equivalents of [AuCl(tht)] (tht = tetrahydrothiophene) leads to the formation of gold(I) complexes [(AuCl)nL] (n = 1-4, 1-4) in which the ligand coordinates up to four gold(I) chloride fragments. Complexes 1-4 show dynamic behaviour with redistribution of {AuCl} moieties which was investigated by 31P{1H} NMR spectroscopy, DFT calculations and single crystal as well as powder X-ray diffraction.

Three Si-substituted polyoxovanadates as efficient catalysts for Knoevenagel condensation and selective oxidation of styrene to benzaldehyde.

Three new Si-substituted polyoxovanadates (POVs), [Cd2(dien)2][Cd(dien)][Cd(Hdien)2][V15Si6O46(OH)2(H2O)]·7H2O (1), [Co(enMe)2]3[Co2(enMe)2(H2O)2][V16Si4O44(OH)2(H2O)]·6H2O (2), and [Co(teta)]4[V16Si4O42(OH)4(H2O)]·10H2O (3) (dien = diethylenetriamine; enMe = 1,2-diaminopropane; teta = triethylenetetramine) were synthesized by the hydrothermal method and characterized. Structural analysis sheds light on the fact that the {V15Si6O48}/{V16Si4O46} clusters of compounds 1-3 were formed by replacing {VO5} square pyramids in the classical {V18O42} cluster with {Si2O7} units. Compound 1 is a 2D bilayer structure formed by the [V15Si6O46(OH)2(H2O)]10- cluster and two types of bridging Cd complexes containing binuclear groups [Cd2(dien)2]4+. Compound 2 is a 3D framework constructed from the [V16Si4O44(OH)2(H2O)]10- cluster and two types of Co complex fragments including binuclear [Co2(enMe)2(H2O)2]4+. In compound 3, the [V16Si4O42(OH)4(H2O)]8- cluster is connected with bridging [Co(teta)]2+ to expand into a 2D network. Compounds 1 and 3 represent the first 2D assemblies based on a vanadosilicate cluster. 1-3 served as heterogeneous catalysts and exhibited highly efficient catalytic activities for the Knoevenagel condensation under mild ambient conditions with low catalyst loading, featuring the open Lewis base {V15Si6O48}/{V16Si4O46} sites and Lewis acid Cd2+/Co2+ sites. The conversion of benzaldehyde was up to 99.3% in 80 min at room temperature using 1 as a heterogeneous catalyst with only 0.37% catalyst loading. Moreover, compounds 1-3 as catalysts for selective oxidation of styrene to benzaldehyde exhibited excellent catalytic performance, high selectivity and could be readily recycled. Most strikingly, compound 1 showed excellent catalytic performance with 97.6% conversion of styrene and 100% selectivity of benzaldehyde in 15 min. In addition, the catalytic activity of catalyst 1 was well maintained after five cycling reactions.

Study on Numerical Simulation Methods for Hypervelocity Impact on Large-Scale Complex Spacecraft Structures

This paper aims to study the difference of results in breakup state judgment, debris cloud and fragment characteristic parameter during hypervelocity impact (HVI) on large-scale complex spacecraft structures by various numerical simulation methods. We compared the results of the test of aluminum projectile impact on an aluminum plate with the simulation results of the smooth particle hydrodynamics (SPH), finite element method (FEM)-smoothed particle Galerkin (SPG) fixed coupling method, node separation method, and finite element method-smooth particle hydrodynamics adaptive coupling method under varying mesh/particle sizes. Then based on the test of the complex simulated satellite under hypervelocity impact of space debris, the most applicable algorithm was selected and used to verify the accuracy of the calculation results. It was found that the finite element method-smooth particle hydrodynamics adaptive coupling method has lower mesh sensitivity in displaying the contour of the debris cloud and calculating its characteristic parameters, making it more suitable for the full-scale numerical simulation of hypervelocity impact. Moreover, this algorithm can simulate the macro breakup state of the full-scale model with complex structure and output debris fragments with clear boundaries and accurate shapes. This study provides numerical simulation method options for the follow-up research on breakup conditions, damage effects, debris clouds, and fragment characteristics of large-scale complex spacecraft.

Paramagnetic 7Li NMR Shifts and Magnetic Properties of Divalent Transition Metal Silylamide Ate Complexes [LiM{N(SiMe3)2}3] (M2+ = Mn, Fe, Co).

7Li NMR shifts and magnetic properties have been determined for three so-called ate complexes [LiM{N(SiMe3)2}3] (M2+ = Mn, Fe, Co; e.g., named lithium-tris(bis(trimethylsilylamide))-manganate(II) in accordance with a formally negative charge assigned to the complex fragment [M{N(SiMe3)2}3]-, which comprises the transition metal). They are formed by addition reactions of LiN(SiMe3)2 and [M{N(SiMe3)2}2] and stabilized by Lewis base/Lewis acid interactions. The results are compared to those of the related "ion-separated" complexes [Li(15-crown-5)][M{N(SiMe3)2}3]. The ate complexes with the lithium atoms connected to the 3d metal atoms manganese, iron, or cobalt via μ2 nitrogen bridges reveal strong 7Li NMR paramagnetic shifts of about -75, 125, and 171 ppm, respectively, whereas the shifts for the lithium ions coordinated by the 15-crown-5 ether are close to zero. The observed trends of the 7Li NMR shifts are confirmed by density-functional theory calculations. The magnetic dc and ac properties display distinct differences for the six compounds under investigation. Both manganese compounds, [LiMn{N(SiMe3)2}3] and [Li(15-crown-5)][Mn{N(SiMe3)2}3], display almost pure and ideal spin-only paramagnetic behavior of a 3d5 high-spin complex. In this respect slightly unexpected, both complexes show slow relaxation behavior at low temperatures under applied dc fields, which is especially pronounced for the ate complex [LiMn{N(SiMe3)2}3]. Dc magnetic properties of the iron complexes reveal moderate g-factor anisotropies with small values of the axial magnetic anisotropy parameter D and a larger E (transversal anisotropy). Both complexes display at low temperatures and, under external dc fields of up to 5000 Oe, only weak ac signals with no maxima in the frequency range from 1 to 1500 s-1. In contrast, the two cobalt complexes display strong g-factor anisotropies with large values of D and E. In addition, in both cases, the ac measurements at low temperatures and applied dc fields reveal two, in terms of their frequency range, well separated relaxation processes with maxima lying for the most part outside of the measurement range between 1 and 1500 s-1.

Total Synthesis of Shearinines D and G: A Convergent Approach to Indole Diterpenoids

AbstractThe first total syntheses of the indole diterpenoids (+)‐shearinine G and D are disclosed. The successful routes rely on late‐stage coupling of two complex fragments. Formation of the challenging trans‐hydrindane motif was accomplished by diastereoselective, intramolecular cyclopropanation. A one‐pot sequence consisting of Sharpless dihydroxylation/Achmatowicz reaction was developed to install the dioxabicyclo[3.2.1]octane motif. The indenone subunit was accessed by Prins cyclization. Tuning the electronic nature of the substituents on the parent arylcarboxaldehyde allowed access to divergent products that were further transformed into shearinines G and D. Riley‐type oxidation of a bicyclic enone yielded a surprising stereochemical outcome.

Total Synthesis of Shearinines D and G: A Convergent Approach to Indole Diterpenoids

The first total syntheses of the indole diterpenoids (+)‐shearinine G and D are disclosed. The successful routes rely on late‐stage coupling of two complex fragments. Formation of the challenging trans‐hydrindane motif was accomplished by diastereoselective, intramolecular cyclopropanation. A one‐pot sequence consisting of Sharpless dihydroxylation/Achmatowicz reaction was developed to install the dioxabicyclo[3.2.1]octane motif. The indenone subunit was accessed by Prins cyclization. Tuning the electronic nature of the substituents on the parent arylcarboxaldehyde allowed access to divergent products that were further transformed into shearinines G and D. Riley‐type oxidation of a bicyclic enone yielded a surprising stereochemical outcome.