N-Heterocyclic carbene-catalyzed enantioselective synthesis of planar-chiral cyclophanes via dynamic kinetic resolution.

Planar-chiral cyclophanes have gained considerable concerns for drug discovery due to their unique conformational strain and 3D structure. However, the enantioselective synthesis of planar-chiral cyclophanes is a long-standing challenge for the synthetic community. We herein describe an N-heterocyclic carbene (NHC)-catalyzed asymmetric construction of planar-chiral cyclophanes. This transformation occurs through a dynamic kinetic resolution (DKR) process to convert racemic substrates into planar-chiral macrocycle scaffolds in good to high yields with high to excellent enantioselectivities. The ansa chain length and aromatic ring substituent size is crucial to achieve the DKR approach. Controlled experiments and DFT calculations were performed to clarify the DKR process.

α-α Coupling-Dominated PPy Film with a Well-Conjugated Structure for Superlong Cycle Life Supercapacitors.

As the electrode of a supercapacitor, polypyrrole (PPy) inevitably suffers from structural rupture during repeated doping/dedoping processes and releases low practical capacitance due to the large amount of aggregation or cross-linking in PPy chains. The coupling mode (α-α, α-ß, or ß-ß coupling) of pyrroles is critical to the conjugated structure, the conductivity, and cycling stability of PPy. Here, we prepared an α-α coupling-dominated PPy film via simple frozen interfacial polymerization. The PPy film with a nanostructure exposes more electrochemical active sites for the electrode, which can enhance the practical capacitance. The high proportion of the α-α coupling mode results in a high degree of large π-conjugation and a planar structure that can effectively improve the reversible ion transport efficiency and promote uniform stress distribution during the charge and discharge process. The assembled symmetric water-based supercapacitor delivers a high specific capacitance of 267.1 F g-1 at 1 A g-1 and 266.7 F g-1 at 5 A g-1 and exhibits an outstanding cycling performance of above 200 F g-1 even after 60,000 cycles.

Palladium-Catalyzed Enantioselective C-H Olefination to Access Planar-Chiral Cyclophanes by Dynamic Kinetic Resolution.

Planar-chiral cyclophanes have received increasing attention for drug discovery and catalyst design. However, the catalytically asymmetric synthesis of planar-chiral cyclophanes has been a longstanding challenge. We describe the first Pd(II)-catalyzed enantioselective C-H olefination of prochiral cyclophanes. The low rotational barrier of less hindered benzene ring in the substrates allows the reaction to proceed through a dynamic kinetic resolution. This approach exhibits broad substrate scope, providing the planar-chiral cyclophanes in high yields (up to 99 %) with excellent enantioselectivities (up to >99 % ee). The ansa chain length scope studies reveal that the chirality of the cyclophanes arises from the bond rotation constraint of the benzene ring around the macrocycle plane, rather than the C-N axis. The C-H activation approach is also applicable to the late-stage modification of bioactive molecules and pharmaceuticals.

A Case of TKA Failure in Patient with Primary Hyperparathyroidism.

BACKGROUND: Primary hyperparathyroidism (PHPT) is an endocrine disorder with high serum calcium and parathyroid hormone (PTH) levels. Excessive secretion of PTH can cause bone loss and may have potential damage to implant fixation after total knee arthroplasty (TKA). However, there is currently no research or literature reporting prosthesis loosening after TKA associated with PHPT. CASE PRESENTATION: This case report describes a TKA failure of tibial prothesis loosening associated with PHPT. The patient faced aggravated pain and difficulty in walking 6 months after the primary TKA. Further examinations showed high serum calcium and PTH levels indicating the presence of PHPT. After the surgery of parathyroidectomy, the patient received revision TKA with 3D-printed metaphyseal cone. Knee symptoms and function were finally improved. CONCLUSION: PHPT is a risk factor for prosthesis loosening after TKA. Preoperative screening test of serum calcium and PTH levels is important to diagnose PHPT. For patients with PHPT undergoing TKA, preoperative endocrinotherapy and parathyroidectomy are recommended to improve the survival of prosthesis.

Flow-cytometric cell sorting coupled with UV mutagenesis for improving pectin lyase expression.

Introduction: Alkaline pectin lyase is an important enzyme with a wide range of applications in industrial production, It has been widely used in many important fields such as fruit juice processing and extraction, the dyeing and processing of cotton and linen textiles, degumming plant fibers, environmental industrial wastewater treatment, and pulp and paper production. PGLA-rep4 was previously generated as a modified alkaline pectin lyase with high specific activity at pH 11.0°C and 70°C. However, the pre-constructed high-activity pectin lyase expression strains are still difficult to apply in industrial production due to their limited enzymatic activity. We hope to solve these problems by combining modern breeding techniques with high-throughput equipment to rapidly screen alkaline pectin lyase with higher enzymatic activity and lower cost. Methods: We fused the genes encoding PGLA-rep4 and fluorescent protein egfp using a flexible linker peptide and ligated them into a temperature-sensitive plasmid, pKD46. The constructed screening plasmid pKD46-PGLA-rep4-egfp was then transformed into an expression host and screened via flow-cytometric cell sorting coupled with UV mutagenesis. Results: Following mutagenesis, primary screening, and secondary screening, the high-expression strain, named Escherichia coli BL21/1G3, was obtained. The screening plasmid pKD46-PGLA-rep4-egfp was eliminated, and the original expression plasmid pET28a-PGLA-rep4 was then retransformed into the mutant strains. After induction and fermentation, pectin lyase activity in E. coli BL21/1G3 was significantly increased (1.37-fold relative to that in the parental E. coli BL21/PGLA-rep4 strain, p < 0.001), and the highest activity was 230, 240 U/mL at 144 h. Genome sequencing revealed that genes encoding ribonuclease E (RNase E) and diadenosine tetraphosphatase (ApaH) of E. coli BL21/1G3 were mutated compared to the sequence in the original E. coli BL21 (DE3) strain, which could be associated with increased enzyme expression. Discussion: Our work provides an effective method for the construction of strains expressing pectin lyase at high levels.

Stability of Three-Dimensional Printed Custom-Made Metaphyseal Cone for Tibial Bone Defects Reconstruction: A Finite Element Analysis and Biomechanical Study.

OBJECTIVES: The reconstruction of bone defects in tibial revision knee arthroplasty is challenging. In this study, we evaluated the primary stability of a novel three-dimensional (3D)-printed custom-made metaphyseal cone for Anderson Orthopedic Research Institute (AORI) IIb or III bone defect reconstruction in tibial revision knee arthroplasty using the combination of finite-element analysis and biomechanical experiments. METHODS: In the finite-element analysis, AORI II b and III medial tibial bone defects were designed at varying depths. A novel 3D-printed custom-made metaphyseal cone was designed and used to reconstruct the bone defect with or without a stem in simulated revision total knee arthroplasty (RTKA). A no-stem group and a stem group were established (based on whether a stem was used or not). Von Mises stress and micromotion were calculated with varying depths of bone defects, ranging from 5 mm to 35 mm, and then micromotions at the bone-implant interface were calculated and compared with the critical value of 150 µm. In the biomechanical experiment, the no-stem group was used, and the same bone defects were made in four synthetic tibias using patient-specific instruments. Micromotions at the bone-implant interface were investigated using a non-contact optical digital image correlation system and compared with the critical value of 150 µm. RESULTS: When the bone defect was <30 mm, micromotions at the bone-implant interface in the finite-element analysis were all below 150 µm both in the stem groups and no-stem groups, whereas those in the biomechanical experiment were also below 150 µm in the no-stem group. CONCLUSIONS: The 3D-printed custom-made metaphyseal cone in RTKA has excellent primary stability and does not require stems in reconstructing tibial AORI type IIb or III bone defects with a depth of <30 mm.

Affinity difference determines the assembly and interaction mode of anammox community reconstructed by siderophores.

Anammox community is the core of anammox process. The constancy of the anammox community determines the stability of the anammox process and the ability of withstand environmental impact. Community stability is influenced by the assembly and interaction mode of the community. This study aimed to explore the assembly, interaction mode, and stability of anammox community influenced by two siderophores (enterobactin and putrebactin) specific for Ca. Brocadia and Ca. Kuenenia as produced in our previous research. Siderophores improved the stability of the anammox community, among which vulnerability dropped by 30.02 % and 72.53 % respectively. Enterobactin and putrebactin altered the succession speed and assembly pattern of communities, with a respective increase of 9.77 % and 80.87 % in the deterministic process of anammox community assembly, respectively. Enterobactin and putrebactin reduced the dependence of Ca. Brocadia and Ca. Kuenenia on companion bacteria by 60 items and 27 items respectively. The affinity of different siderophore-Fe with bacterial membrane receptors caused variations in community reconstruction, with Ca. Brocadia and Ca. Kuenenia exhibiting the highest affinity with enterobactin-Fe (-11.4 kcal/mol) and putrebactin-Fe (-9.0 kcal/mol), respectively. This study demonstrated how siderophores can enhance the stability of anammox process by regulating assembly and interaction mode of anammox community, while also revealing the underlying molecular mechanisms.

Directed regulation of anammox communities based on exogenous siderophores for highly efficient nitrogen removal.

It is expected that the quicker domestication of anaerobic ammonia oxidation (anammox) communities and the enhancement of their nitrogen transformation capability can be achieved through targeted regulation of anammox communities. Iron cast a vital role in the growth and metabolism of anammox bacteria. Specific siderophores offer promising prospects for the targeted regulation of anammox communities by facilitating the efficient utilization of iron. Two siderophores-enterobactin and putrebactin-exclusively for Ca. Brocadia and Ca. Kuenenia were developed to specifically regulate anammox communities towards different directions, respectively. Anammox communities in the reactors evoluted targetedly towards Ca. Brocadia-dominated communities and Ca. Kuenenia-dominated communities, respectively, leading to a maximum increase in community nitrogen removal capacity by 84.64±0.55% and 210.26±0.57%, respectively, under different nitrogen concentrations. It was indicated that siderophores could regulate anammox communities by redistributing iron resources in a targeted manner based on the analyses of transcriptome and proteome. This study provides novel insights into the rational selection and utilization of exogenous siderophores as an effective implement to manipulate anammox communities and create communities with high nitrogen removal ability fleetly.

[Research Progress in Application of Patient-Reported Outcome Measures in Total Knee Arthroplasty].

To summarize the clinical application of patient-reported outcome measures (PROM) in total knee arthroplasty (TKA) and provide reference for the application of PROM in perioperative evaluation of the patients receiving TKA,we reviewed the recent studies about the application of PROM in TKA and analyzed the contents and application characteristics of the PROM.The common PROM in TKA,such as the Western Ontario and McMaster Universities Osteoarthritis Index,Oxford Knee Score,and Forgotten Joint Score,principally focus on patients' subjective feelings about pain,function and other aspects of their knees.However,they have diverse ranges of application and each of them has their own advantages and disadvantages.There is a variety of PROM applied in TKA,which makes it challenging to select the proper measurement for evaluation.The PROM in TKA remains to be improved for broader use.

A Review on Generation and Reactivity of the N-Heterocyclic Carbene-Bound Alkynyl Acyl Azolium Intermediates.

N-heterocyclic carbene (NHC) has been widely used as an organocatalyst for both umpolung and non-umpolung chemistry. Previous works mainly focus on species including Breslow intermediate, azolium enolate intermediate, homoenolate intermediate, alkenyl acyl azolium intermediate, etc. Notably, the NHC-bound alkynyl acyl azolium has emerged as an effective intermediate to access functionalized cyclic molecular skeleton until very recently. In this review, we summarized the generation and reactivity of the NHC-bound alkynyl acyl azolium intermediates, which covers the efforts and advances in the synthesis of achiral and axially chiral cyclic scaffolds via the NHC-bound alkynyl acyl azolium intermediates. In particular, the mechanism related to this intermediate is discussed in detail.

Correction: Catalytic (3 + 2) umpolung annulations of α-thioacyl carbenes with aryl isothiocyanates.

Correction for 'Catalytic (3 + 2) umpolung annulations of α-thioacyl carbenes with aryl isothiocyanates' by Ziyang Dong et al., Chem. Commun., 2022, 58, 7980-7983, https://doi.org/10.1039/D2CC02882D.

Catalytic (3 + 2) umpolung annulations of α-thioacyl carbenes with aryl isothiocyanates.

1,2,3-Thiadiazoles serve as masked S-electrophilic thia-1,3-dipoles. Under rhodium/racemic BINAP catalysis, they undergo denitrogenative (3 + 2) umpolung transannulations with aryl isothiocyanates with inverse regioselectivity and excellent stereoselectivity, yielding N-aryl 3H-1,2-dithiol-(Z)-3-imines in a redox-neutral, step-efficient, and functionality-tolerant manner. An intramolecular S-S bond is impressively forged.

Catalytic Diastereospecific and Enantioselective (3 + 2) Transannulations of 1,2,3-Thiadiazoles with Strained Norbornene Derivatives.

With the adoption of a ring-strain-release strategy, iridium-catalyzed transannulations with norbornene derivatives are achieved in a diastereospecific and enantioselective manner. The first asymmetric transannulations of 1,2,3-thiadiazoles are reported.

The effect of tourniquet application on the morphology and function of quadriceps in patients undergoing total knee arthroplasty: study protocol for a single-blind randomized controlled trial.

BACKGROUND: Tourniquet is currently widely used in total knee arthroplasty to reduce intraoperative blood loss. The academic view of tourniquet application in TKA is now in dispute. Some scholars argue that tourniquet may cause quadriceps injury and bring extra side effects, so they oppose the application of tourniquet. Others find that tourniquet application has no significant adverse impact on TKA patients. Regarding its advantages in reducing intraoperative blood loss, they advocate the regular application of tourniquet in TKA. Quadriceps injury is considered the main cause of tourniquet side effects. There are now many high-quality trials about tourniquet application in TKA but few of them concentrate on quadriceps morphology and function. METHODS: A prospective, single-blind, randomized controlled trial will be adopted. The target sample is 130. Patients who meet the eligibility criteria will be randomly allocated to the tourniquet group and non-tourniquet group. The primary outcome is quadriceps thickness evaluated by ultrasound test. Secondary outcomes include quadriceps stiffness, rehabilitation outcomes, operation time, intraoperative and postoperative blood loss, blood transfusion rate, thigh circumference, VAS score, opioid consumption, D-dimer and C-reactive protein level in the serum, knee function score, postoperative satisfaction score, and complications. DISCUSSION: This proposed study will contribute to improve evidence of tourniquet application in total knee arthroplasty. This will be a high-quality single-blind randomized controlled trial with a sufficient sample size and strict study design. It will investigate the effects of tourniquet application especially on the morphology and function of quadriceps in patients undergoing total knee arthroplasty and offer advice for tourniquet application in clinical practice. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2000035097 . Registered on 31 July 2020.

[Research progress on comparison of the application effects between personal specific instrumentation and computer-assisted navigation surgery in total knee arthroplasty].

OBJECTIVE: To compare the application effects between personal specific instrumentation (PSI) and computer-assisted navigation surgery (CAS) in total knee arthroplasty (TKA). METHODS: The literature comparing the application effects of PSI and CAS in TKA in recent years was widely consulted, and the difference between PSI-TKA and CAS-TKA in operation time, lower limb alignment, blood loss, and knee function were compared. RESULTS: Compared to CAS-TKA, PSI-TKA simplifies operation procedures and shortens operation time but probably has worse lower limb alignment. It is still controversial in comparison of perioperative blood loss and knee function between two techniques. CONCLUSION: PSI-TKA and CAS-TKA both have advantages and disadvantages, and their differences need to be confirmed by further high-quality clinical trial.

Effect of temperature decrease on anammox granular sludge: Shock and adaptation.

Cryopreservation is one of the effective methods for the preservation of anammox granular sludge (AnGS). However, the effects of cooling pretreatment on AnGS are still unclear. In this study, the effects of temperature decrease on AnGS property were investigated by designing different cooling modes: constant at room temperature 20-25 °C (CK), sharp cooling to 4 °C (S4), -20 °C (S20) and stepwise cooling to 4 °C (A4), -20 °C (A20). The results showed that compared with CK, the cooling modes in S4, S20, A4 and A20 improved the physical preservability of AnGS, slowing down the changes of color, shape and structure; and elevated the preservation rate of functional bacteria Planctomycetes (phylum level) and Candidatus Brocadia (genus level). The preservation rate of live cells in different experimental groups was 48.4 ± 1.8%(CK), 61.1 ± 3.3%(S4), 37.8 ± 0.8%(S20), 81.7 ± 4.8%(A4), 61.9 ± 3.1%(A20), respectively. The Anaerobic Ammonium Oxidation Bacteria (AnAOB) in the stepwise cooling mode (A4 and A20) were found to enter the dormant state and form "dormant zoogloea", while the AnAOB in the sharp cooling mode (S4 and S20) were observed to enter the shock state with a little change. The findings in this work (especially the dormant state of AnAOB) are helpful to understand the effect of temperature decrease on AnGS and to promote the development of AnGS preservation technology.

Sulfur-controlled and rhodium-catalyzed formal (3 + 3) transannulation of thioacyl carbenes with alk-2-enals and mechanistic insights.

A rhodium-catalyzed denitrogenative formal (3 + 3) transannulation of 1,2,3-thiadiazoles with alk-2-enals is achieved, producing 2,3-dihydrothiopyran-4-ones in moderate to excellent yields. An inverse KIE of 0.49 is obtained, suggesting the reversibility of the oxidative addition of thioacyl Rh(i) carbenes to alk-2-enals. The late-stage structural modifications of steroid compounds are realized. Moreover, our studies show that thioacyl carbenes have different reactivities to those of α-oxo and α-imino carbenes, and highlight the importance of heteroatoms in deciding the reactivities of heterovinyl carbenes.

[Regulation of microbial siderophore transport and its application in environmental remediation].

Siderophore is a chelating iron substance secreted by microorganisms at low intracellular iron concentration. Siderophore can be divided into three categories: catechol salts, hydroxamic salts and carboxylates. The transport of siderophore is regulated by Fur, σ factor and quorum sensing signal. In recent years, siderophore has been used in fields such as oil pollution remediation, heavy metal pollution remediation and pulp biological bleaching, and has received extensive attention. This paper reviews the classification of siderophores and their transport regulation mechanism, and the application of siderophore in environmental pollution control and remediation. Furthermore, we address the application of siderophore in the future.

Rhodium-Catalyzed 1,1-Hydroacylation of Thioacyl Carbenes with Alkynyl Aldehydes and Subsequent Cyclization.

A rhodium-catalyzed 1,1-hydroacylation of thioacyl carbenes with alkynyl and alkenyl aldehydes and subsequent 6- endo-trig/dig cyclization are realized, giving structurally diverse 4 H-thiopyran-4-ones and 2,3-dihydro-4 H-thiopyran-4-ones in moderate to good yields. The oxidative addition of Rh(I) to aldehydes is proposed to be the turnover-limiting step. Manipulations of estrones demonstrate the applications of our formal (3 + 3) transannulations in the structural modifications of natural products.

Complex Iron Uptake by the Putrebactin-Mediated and Feo Systems in Shewanella oneidensis.

Shewanella oneidensis is an extensively studied bacterium capable of respiring minerals, including a variety of iron ores, as terminal electron acceptors (EAs). Although iron plays an essential and special role in iron respiration of S. oneidensis, little has been done to date to investigate the characteristics of iron transport in this bacterium. In this study, we found that all proteins encoded by the pub-putA-putB cluster for putrebactin (S. oneidensis native siderophore) synthesis (PubABC), recognition-transport of Fe3+-putrebactin across the outer membrane (PutA), and reduction of ferric putrebactin (PutB) are essential to putrebactin-mediated iron uptake. Although homologs of PutA are many, none can function as its replacement, but some are able to work with other bacterial siderophores. We then showed that Fe2+-specific Feo is the other primary iron uptake system, based on the synthetical lethal phenotype resulting from the loss of both iron uptake routes. The role of the Feo system in iron uptake appears to be more critical, as growth is significantly impaired by the absence of the system but not of putrebactin. Furthermore, we demonstrate that hydroxyl acids, especially α-types such as lactate, promote iron uptake in a Feo-dependent manner. Overall, our findings underscore the importance of the ferrous iron uptake system in metal-reducing bacteria, providing an insight into iron homeostasis by linking these two biological processes.IMPORTANCES. oneidensis is among the first- and the best-studied metal-reducing bacteria, with great potential in bioremediation and biotechnology. However, many questions regarding mechanisms closely associated with those applications, such as iron homeostasis, including iron uptake, export, and regulation, remain to be addressed. Here we show that Feo is a primary player in iron uptake in addition to the siderophore-dependent route. The investigation also resolved a few puzzles regarding the unexpected phenotypes of the putA mutant and lactate-dependent iron uptake. By elucidating the physiological roles of these two important iron uptake systems, this work revealed the breadth of the impacts of iron uptake systems on the biological processes.