bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study of Efficacy of Oral Terbinafine and Oralitraconazole in Tinea Corporis / Tinea Cruris Infection
Authors: Brigida S. , Elizabeth Arul Amutha
Published: April 2021

Dermatophytoses which are superficial fungal infections of the skin, hair, and nail are among the most common infective dermatoses seen in dermatology outpatient clinics. Today, we are facing an onslaught of chronic and recurrent dermatophytosis in volumes never encountered previously. Itraconazole was found to be the  better antifungal  in terms of clinical cure,mycological  clearance  and less need for extension of treatment than Terbinafine. Overall, oral Itraconazole 200 mg/day for 2 weeks proved to be a better agent with excellent and significantly better cure rates than  oral Terbinafine 500mg/day for 2 weeks. With Itraconazole, the contra-indications, drug  interactions must be kept in mind to prevent loss of efficacy/ potentially hazardous interactions. Both drugs had a good safety profile and few minor adverse events. The reasons for  extension of treatment comprise chronicity, previous treatment with OTC steroid preparations, and misuse of systemic antifungal drugs, diabetes, and obesity. Poor personal practices and hygiene also havetheir contribution. Significant associations were also noted between diabetes and chronicity.
Study of Expression of P53 in Prostatic Lesions
Authors: Preethi M. , Jayaraman . , Ganapathy Hemalatha , Lilly S. Mary
Published: April 2021

Prostate gland is an accessory gland of the male reproductive system.Prostate begins development from the mesenchymal tissue, surrounding the urogenital sinus in the 3 rd month of gestation. Epithelial buds invaginate from the posterior sinus on either side of verumontanum. Concurrently, Wolffian ducts develop into seminal vesicles, epididymis, Vasdeferens and ejaculatory ducts that are stimulated by fetal testosterone. Histologically all malignant lesions encountered were Conventional Adenocarcinoma of Prostate. The commonest pattern seen was acinar followed bycribriform and fused glandularpattern. Conventional Adenocarcinoma forms the most commontype of prostatic carcinoma and they are moderately differentiated byGleason’s microscopicgrading. Serum Prostate Specific Antigen (PSA) levels increases proportionately with advancing clinical stage. Studies have shownthat serial increase in serum PSA is associated with incidence of occult carcinoma.In the present study, the TURP specimen received was ranged in the volume from 8 to 20cc. Every tissue was carefully examined for the presence of yellow and firm or gray hard areas and necrotic areas. After fixation and processing, 4 -5µ sections were cut and Hematoxylin and Eosin staining was done. In the present study all the benign lesions stained negative except for cases  were the  PSA  value is  more than  >50ng/ml with  p53 IHC and in prostate carcinoma positive indicating epithelial marker positive for prostate gland. In coclusio, the IHC expression of p53 is significantly up- regulated in malignant lesions and have importance in prognostic factors and disease survival.
The Role p53 Protein Expression in Urothelial Neoplasm
Authors: Sahoo Bijayalaxmi , Jayaraman . , Govindharajan R. , Sivastava Vindu
Published: April 2021

The urinary bladder had a line with transitional epithelium. Urothelial neoplasms are the majority among the bladder neoplasms. Urothelial neoplasms were more common in males than in females. Urothelial neoplasms usually occur in the elderly age group. The majority of the tumor size was more significant than 3 cm, and papillary type is majorly found among the tumors. The present study aimed to identify the grade and staging of the p53 in urothelial neoplasms.

The bladder carcinoma (54) cases from Department of Pathology, Sree Balaji Medical College and hospital (during September 2015 to September 2017) were analysed. The median age for bladder carcinoma in the present study was 66 years. The clinical parameter studied was the size of the lesion based on the cytoscopic or radiological findings (31- 33). Based on tumor size, lesions were classified into two groups, less than equal to 3cm and greater than 3cm, which was found to be 42% and 58%, respectively This study concludes that p53 is useful in differentiating benign and malignant neoplasms in morphologically difficult cases. Immunohistochemistry for p53 is useful adjunct to histomorphology.
Emergency Treatment of Patients of Thoraco Abdominal Trauma in Surgical Ward According to Advanced Trauma and Life Support (ATLS)
Authors: Laghari Ahsan Ali , Shaikh Shiraz , Abro Shahnawaz , Suhail Muhammad Ali , Memon Gulshan Ali , Khaskheli Ghulam Akbar , Ahmer Arslan
Published: April 2021

Objective: To determine the emergency treatment of Patients of Thoraco abdominal trauma in surgical ward according to Advance trauma and life support (ATLS).

Methodology: Prospective observational study was conducted for two years from April 2018 to March 2020 at Liaquat university of Medical and Health Sciences Jamshoro/Hyderabad Hospital. The study comprises 50 patients. All were admitted from Emergency department. The patients were evaluated fully after history & clinical examinations. Results were analyzed by using statistical package for social sciences (SPSS) version 23.

Results: In this study of 50 patients of Thoraco abdominal trauma, the maximum numbers of patients were in age group 15-70 years. Out of 50 patients 25 patients were presented with Trauma in Thorax, in which 5 patients were presented with penetrating injury & 20 patients were presented with Blunt trauma, 10 patients were presented with combine Thoraco abdominal trauma in which 2 patient were presented with penetrating injury & 8 patients were presented with Blunt trauma. Related to chest trauma 10 patients were treated needle thoracotomy with chest intubation, 5 patients were treated endotracheal intubation, 3 patients were treated thoracotomy and 2 patients were treated cardiosentesis, 5 patients were treated cricothyroidotomy. Better out were seen in 45 patients and mortality were seen in 5 patients.

Conclusion: Advance trauma and life support (ATLS) has a vital role in thoraco abdominal trauma intervention. 90% of successful interventions were obtained using advance trauma and life support.
A Safety Management Case of Laparoscopic Colectomy in a Patient With Paroxysmal Nocturnal Hemoglobinuria
Authors: Matsuno Hiroshi , Hata Taishi , Takahashi Hidekazu , Haraguchi Naotsugu , Uemura Mamoru , Nishimura Junichi , Takemasa Ichiro , Mizushima Tsunekazu , Yamamoto Hirofumi , Doki Yuichiro , Mori Masaki
Published: April 2021

Paroxysmal nocturnal hemoglobinuria is a rare and life-threatening disorder of acquired hemolytic anemia. Surgery is one of the major clinical situations that trigger hemolytic attack. Eculizumab is a humanized monoclonal antibody that binds the complement protein C5 and prevents complement-mediated hemolysis via inhibition of the terminal complement cascade. A 76-year-old woman received a diagnosis of ascending colon cancer during the search for the cause of right lower abdominal pain. She had received a diagnosis of paroxysmal nocturnal hemoglobinuria and been followed for 26 years at our hospital. We planned to start eculizumab for perioperative management in order to reduce the risk of the patient developing hemolytic crisis as a result of surgery. We administered 600 mg of eculizumab on the 15th, 8th, and 1st preoperative days. The levels of serum complement and lactate dehydrogenase decreased with the first administration of eculizumab. Laparoscopic right hemicolectomy was performed successfully. The patient had good postoperative progress. We administered 600 mg of eculizumab on the 6th postoperative day and 900 mg of eculizumab on the 13th postoperative day. She was discharged from hospital on the 16th postoperative day. We started use of eculizumab before surgery for safety in the management of the operation and during the perioperative period. When we enforce the elective operation for patients with paroxysmal nocturnal hemoglobinuria who do not start treatment of eculizumab, we recommend the use of eculizumab for perioperative management of patients with paroxysmal nocturnal hemoglobinuria.
Wandering Gallbladder: A Case Report
Authors: Kopp Miroslav , Cornish Nathan A. , Nazir Sharique
Published: April 2021

Wandering gallbladder is a variation in the biliary anatomy described in the literature as being attached only by the cystic duct and its mesentery. Its propensity for torsion places it at risk for necrosis. There have been over 500 cases of gallbladder torsion reported in the literature but less than 10 reports of wandering gallbladder. To our knowledge there have been no reports of cholecystectomy for wandering gallbladder found incidentally. A 51-year-old male from Pakistan with hypertension, gastroesophageal reflux disease, high cholesterol, and renal stones presented with a chief complaint of right upper quadrant abdominal pain. Abdominal ultrasound was significant for a mildly distended gallbladder with small gallstones in the gallbladder fundus. The patient was discharged with a diagnosis of cholelithiasis and scheduled for laparoscopic cholecystectomy as an outpatient. During the procedure, upon entering the abdominal cavity, a gallbladder was not seen in the gallbladder fossa. It was attached to the cystic duct, thickened with a long mesentery and not attached to the liver. There were no signs of torsion. The patient was treated successfully and discharged home with an uncomplicated hospital course. Diagnosis can be challenging because the clinical presentation can be variable. Fewer than a dozen cases have been reported where the diagnosis was made preoperatively. Early diagnosis of gallbladder torsion with cholecystectomy is essential to avoid the deadly complications of perforation and bilious peritonitis. Understanding the pathophysiology, clinical findings, and treatment can have a broad impact across biliary surgery in preventing these complications.
Short-Term Outcome of Laparoscopic Surgery in Elderly Colorectal Cancer Patients
Authors: Kitahara Tomohiro , Hata Taishi , Uemura Mamoru , Haraguchi Naotsugu , Motoki Yoshiyuki , Sugimoto Satoshi , Nishimura Junichi , Takemasa Ichiro , Mizushima Tsunekazu , Ikeda Masataka , Yamamoto Hirofumi , Doki Yuichiro , Mori Masaki
Published: April 2021

We aimed to evaluate the short-term outcome of colorectal resection in very elderly patients, aged 85 years or older. As the population ages, the number of elderly patients with colorectal cancer (CRC) is increasing in Japan. At this time, it is unclear whether or not laparoscopic colorectal resection is safe for this very elderly patient population. From January 2005 to November 2014, a total of 20 patients aged 85 years or older underwent laparoscopic colorectal resection at Osaka University Hospital. Pre- and postoperative clinical data and outcomes were collected retrospectively. There were no intraoperative or postoperative deaths. In 2 cases, the laparoscopic procedure was converted to open surgery. Postoperative complications occurred in 6 patients. Two patients developed an infection at the surgical site. Among the 4 patients who underwent low anterior resection (LAR), 2 experienced postoperative anastomotic leakage. Two other patients developed a lung infection and urinary tract infection, respectively. Laparoscopic colectomy for very elderly patients with CRC appears to involve tolerable risk. However, special caution is advisable for patients who may undergo LAR.
Analysis of Related Factors on The Vertebral Height Restoration of Percutaneous Vertebral Augmentation
Authors: Xie Weixing
Published: April 2021

Background

Percutaneous vertebral augmentation (PVA) is widely applied for the treatment of osteoporotic vertebral fractures. The degree of vertebral body height restoration and deformity correction after the procedure is not consistent.

Methods

We retrospectively reviewed 97 patients who underwent PVA, because of osteoporotic vertebral compression fractures. The following data about the patients were recorded: age, sex, bone density, number of treated vertebrae, severity of fracture of the treated vertebrae, operative approach (PVP or PKP), volume of injected bone cement, preoperative vertebral compression ratio, preoperative local kyphosis angle, cement leakage, postoperative vertebral body height restoration ratio, follow-up period, and latest follow-up height loss ratio. Bivariate regression analysis and t-test were applied for univariate analysis, while multivariate linear regression analysis was applied for multivariate analysis.

Results

The postoperative vertebral body height restoration ratio was (14.7% ± 15.2%), and the last follow-up height loss ratio was (13.5% ± 11.5%). The multivariate analysis showed that the number of treated vertebrae, preoperative vertebral compression ratio, and preoperative local kyphosis angle are the main factors influencing the postoperative vertebral body height restoration. The univariate analysis also showed that only the postoperative vertebral body height restoration ratio is related to the last follow-up height loss ratio.

Conclusions

The number of treated vertebrae, preoperative vertebral compression ratio, and preoperative local kyphosis angle are the main influencing factors of patients' vertebral body height restoration after PVA, and the postoperative vertebral body height restoration ratio is the main factor influencing the last follow-up height loss ratio.
Linear‐like properties arise naturally in the adaptive control setting
Authors: Miller Daniel E. , Shahab Mohamad T.
Published: April 2021

Classical discrete‐time adaptive controllers typically provide asymptotic stabilization and tracking; usually the affect of the noise is at best bounded‐input bounded‐output. Recently we have shown that if you design a discrete‐time adaptive controller in just the right way, then in a variety of situations you not only obtain exponential stability, but also a bounded gain on the noise in every p−norm, as well as a never‐before‐seen linear‐like convolution bound on the input–output behavior. Quite surprisingly, the approach is very natural, and relies on the use of the unmodified, original projection algorithm to carry out parameter estimation; if the set of plant uncertainty is not convex, then a multi‐estimator and switching are used. The goal of this paper is to provide an overview of the approach, discuss the results‐to‐date, and list some of the open problems.
Ion Exchange Lithography: Localized Ion Exchange Reactions for Spatial Patterning of Perovskite Semiconductors and Insulators
Authors: Helmbrecht Lukas , Futscher Moritz H. , Muscarella Loreta A. , Ehrler Bruno , Noorduin Willem L.
Published: April 2021

Patterning materials with different properties in a single film is a fundamental challenge and essential for the development of next‐generation (opto)electronic functional components. This work introduces the concept of ion exchange lithography and demonstrates spatially controlled patterning of electrically insulating films and semiconductors with tunable optoelectronic properties. In ion exchange lithography, a reactive nanoparticle “canvas” is locally converted by printing ion exchange “inks.” To demonstrate the proof of principle, a canvas of insulating nanoporous lead carbonate is spatioselectively converted into semiconducting lead halide perovskites by contact printing an ion exchange precursor ink of methylammonium and formamidinium halides. By selecting the composition of the ink, the photoluminescence wavelength of the perovskite semiconductors is tunable over the entire visible spectrum. A broad palette of conversion inks can be applied on the reactive film by printing with customizable stamp designs, spray‐painting with stencils, and painting with a brush to inscribe well‐defined patterns with tunable optoelectronic properties in the same canvas. Moreover, the optoelectronic properties of the converted canvas are exploited to fabricate a green light‐emitting diode (LED), demonstrating the functionality potential of ion exchange lithography.
A Molecular Drone for Atomic‐Scale Fabrication Working under Ambient Conditions
Authors: Baldoni Matteo , Mercuri Francesco , Cavallini Massimiliano
Published: April 2021

The direct manipulation of individual atoms has led to the advancement of exciting cutting‐edge technologies in sub‐nanometric fabrication, information storage and to the exploration of quantum technologies. Atom manipulation is currently performed by scanning probe microscopy (SPM), which enables an extraordinary spatial control, but provides a low throughput, requiring complex critical experimental conditions and advanced instrumentation. Here, a new paradigm is demonstrated for surface atom manipulation that overcomes the limitations of SPM techniques by replacing the SPM probe with a coordination compound that exploits surface atom complexation as a tool for atomic‐scale fabrication. The coordination compound works as a “molecular drone”: it lands onto a substrate, bonds to a specific atom on the surface, picks it up, and then leaves the surface along with the extracted atom, thus creating an atomic vacancy in a specific position on the surface. Remarkably, the feasibility of the process is demonstrated under electrochemical control and the stability of the fabricated pattern at room temperature, under ambient conditions.
2D MXene–Molecular Hybrid Additive for High‐Performance Ambipolar Polymer Field‐Effect Transistors and Logic Gates
Authors: Wang Hanlin , Wang Ye , Ni Zhenjie , Turetta Nicholas , Gali Sai Manoj , Peng Haijun , Yao Yifan , Chen Yusheng , Janica Iwona , Beljonne David , Hu Wenping , Ciesielski Artur , Samorì Paolo
Published: April 2021

MXenes are highly conductive layered materials that are attracting a great interest for high‐performance opto‐electronics, photonics, and energy applications.. Their non‐covalent functionalization with ad hoc molecules enables the production of stable inks of 2D flakes to be processed in thin‐films. Here, the formation of stable dispersions via the intercalation of Ti3C2Tx with didecyldimethyl ammonium bromide (DDAB) yielding Ti3C2Tx–DDAB, is demonstrated. Such functionalization modulates the properties of Ti3C2Tx, as evidenced by a 0.47 eV decrease of the work function. It is also shown that DDAB is a powerful n‐dopant capable of enhancing electron mobility in conjugated polymers and 2D materials. When Ti3C2Tx–DDAB is blended with poly(diketopyrrolopyrrole‐co‐selenophene) [(PDPP–Se)], a simultaneous increase by 170% and 152% of the hole and electron field‐effect mobilities, respectively, is observed, compared to the neat conjugated polymer, with values reaching 2.0 cm2 V−1 s−1. By exploiting the balanced ambipolar transport of the Ti3C2Tx–DDAB/PDPP–Se hybrid, complementary metal–oxide–semiconductor (CMOS) logic gates are fabricated that display well‐centered trip points and good noise margin (64.6% for inverter). The results demonstrate that intercalant engineering represents an efficient strategy to tune the electronic properties of Ti3C2Tx yielding functionalized MXenes for polymer transistors with unprecedented performances and functions.
Tuning the Magic Sizes and Optical Properties of Atomically Precise Bidentate N‐Heterocyclic Carbene‐Protected Gold Nanoclusters via Subtle Change of N‐Substituents
Authors: Luo Peng , Bai Sha , Wang Xin , Zhao Jing , Yan Zhen‐Ning , Han Ying‐Feng , Zang Shuang‐Quan , Mak Thomas C. W.
Published: April 2021

Owing to the atomically precise structures, metal nanoclusters (NCs) have always served as model molecular tools to analyze NC surface chemistry and to investigate structure−property correlations. Herein, a series of bis‐N‐heterocyclic carbene (NHC)‐protected NCs of type [Au11(bis‐NHC)5]3+ and [Au13(bis‐NHC)5Br2]3+ obtained from direct reduction of Au−bis‐NHC complexes are described. The NCs type obtained depends on the N‐wingtip substituents of the Au−bis‐NHC complexes. Subtle changes in the lengths of the N‐wingtip substituents enable the fine‐tuning of the kernel with either Au11 or Au13 clusters. Among them, [Au11(bis‐NHC)5]3+ cluster is the first homoleptic NHC‐stabilized Au NC. The composition and structures of these NCs are unequivocally determined by single crystal X‐ray crystallography and electrospray ionization mass spectrometry. Contrary to the non‐emissive Au11 cluster, the Au13 NC exhibits high emission in solution and the luminescence properties are severely dependent onto the substituent effects. Additionally, peculiar Au⋯HC interactions are present in NHC‐protected clusters.
Switching the Nonparametric Optical Nonlinearity of Tungsten Oxide by Electrical Modulation
Authors: Li Hui , Hou Ruipeng , Sun Yanhui , Diao Mengjuan , Liang Ying , Chen Xin , Huang Zhipeng , Wang Jun , Humphrey Mark G. , Yu Zhiyang , Zhang Chi
Published: April 2021

This work shows the electrical switching of the nonparametric optical nonlinearity of tungsten oxide (WO3−x). The sign and magnitude of the effective nonlinear absorption coefficient (βeff) can be modulated via application of an external bias. With laser excitation at 1030 nm, WO3−x shows a relatively large saturable absorption (SA) under an applied voltage (VA) of −2.5 V, with βeff being as large as −632 cm GW−1, while reverse saturable absorption (RSA) is found for VA larger than −1.5 V. The electrical switching of the nonlinear optical (NLO) response is reproducible and durable. Both electrostatic and electrochemical dopings of WO3−x occur during VA variation, with SA resulting mainly from the electrochemical doping (the intercalation of H+ into the lattice of WO3−x). The wavelength‐dependent NLO performance of pristine WO3−x is attributed to competition between one‐photon absorption and two‐photon absorption, while the VA‐derived NLO response is correlated with variation in the band structure and its population. These results suggest a promising approach for the postsynthesis modulation of the NLO response and a potential device configuration for further optoelectric applications.
Electrophoretic Plasmonic Ink for Dynamic Color Display
Authors: Zheng Jiapeng , Chow Tsz Him , Li Shasha , Wang Jianfang , Shao Lei
Published: April 2021

Plasmonic metal nanostructures generate vivid colors with high spatial resolution. Active control of plasmonic pixels by electrical means, which is compatible with integrated circuit technologies, is a promising technique for dynamic full color reflective display. However, the development of electrical plasmonic display is still limited by the difficulties in cost‐effective construction of active plasmonic pixels over large areas. This study demonstrates the achievement of electrical plasmonic display in full color by electrophoretic movement control of plasmonic noble metal nanocrystals in an organic electrolyte solvent. The persistent issues of nanoparticle aggregation and irreversible deposition in electrophoresis are addressed through appropriate surface modifications of the plasmonic nanocrystals, enabling them as advantageous nanoscale colorful pigments with long‐term durability. A weak electric field therefore allows color display with high contrast, high saturation, and electrical reconfigurability. The ink containing plasmonic pigments is further assembled into microfluidic chips to display different characters. The strategy will pave the way towards the development of plasmonic electronic paper in full color.
Hearing impairment and missing cognitive test scores in a population‐based study of older adults: The Atherosclerosis Risk in Communities neurocognitive study
Authors: Deal Jennifer A. , Gross Alden L. , Sharrett A. Richey , Abraham Alison G. , Coresh Josef , Carlson Michelle , Griswold Michael , Mosley Thomas , Power Melinda C. , Ramulu Pradeep , Reed Nicholas S. , Lin Frank R. , Swenor Bonnielin K.
Published: April 2021

Introduction

Hearing impairment is associated with poor cognitive test performance in older adults. However, hearing's impact on cognitive test completion is poorly described, and missing cognitive data due to hearing impairment could misestimate the association.

Methods

We investigated if hearing impairment is associated with missing neurocognitive scores in 3678 adults (72‐94 years). Hearing impairment was defined by the better‐ear pure tone average of speech‐frequency thresholds (0.5‐4 kHz) >25 decibels.

Results

Hearing impairment was associated with greater missingness on all auditory‐only tests, including Logical Memory (prevalence ratio [PR] comparing ≥ moderate impairment vs normal hearing:1.68, 95% confidence interval [CI] 1.26, 2.25) and Digits Backwards (PR 1.62; 95% CI 1.21, 2.17); and two non‐auditory tests, Boston Naming (PR 1.61; 95% CI 1.21, 2.17) and Trail Making B (PR 1.55; 95% CI 1.29, 1.86). Models that imputed missing cognitive scores showed the strongest hearing‐cognition associations.

Discussion

Older adults with hearing impairment are less likely to complete cognitive testing, thereby underestimating the hearing impairment‐cognition relationship.
Interweaving Visible‐Light and Iron Catalysis for Nitrene Formation and Transformation with Dioxazolones
Authors: Tang Jing‐Jing , Yu Xiaoqiang , Wang Yi , Yamamoto Yoshinori , Bao Ming
Published: April 2021

Herein, visible‐light‐driven iron‐catalyzed nitrene transfer reactions with dioxazolones for intermolecular C(sp3)‐N, N=S, and N=P bond formation are described. These reactions occur with exogenous‐ligand‐free process and feature satisfactory to excellent yields (up to 99 %), an ample substrate scope (109 examples) under mild reaction conditions. In contrast to intramolecular C−H amidations strategies, an intermolecular regioselective C−H amidation via visible‐light‐induced nitrene transfer reactions is devised. Mechanistic studies indicate that the reaction proceeds via a radical pathway. Computational studies show that the decarboxylation of dioxazolone depends on the conversion of ground sextet state dioxazolone‐bounding iron species to quartet spin state via visible‐light irradiation.
Generating Assembled MFI Nanocrystals with Reduced b‐Axis through Structure‐Directing Agent Exchange Induced Recrystallization
Authors: Zhao Xiaoling , Zeng Shu , Zhang Xueliang , Deng Quanzheng , Li Xiujie , Yu Wenguang , Zhu Kake , Xu Shutao , Liu Jichang , Han Lu
Published: April 2021

Controlling crystal size and shape of zeolitic materials is an effective way to promote their mass transport and catalytic properties. Herein, we report a single step, Na+‐ and porogen‐ free crystallization of MFI hierarchical architecture made up of aligned nanocrystals with reduced b‐axis thickness (5–23 nm) and adjustable Si/Al ratios between 35 to 120, employing the commonly used tetrapropylammonium hydroxide (TPAOH) and tetrabutylammonium hydroxide (TBAOH) as structure‐directing agents (SDAs). Homogeneous nucleation driven by both SDAs and subsequent SDA‐exchange induced dissolution‐recrystallization are responsible for the formation of such structure. The enhanced textural and diffusion properties account for a notable exaggeration of propene selectivity and catalyst lifetime in dimethyl ether‐to‐olefins (DTO) conversion. This protocol is extendable to the rational synthesis of other hierarchical zeolites through crystallization process control.
Ligand‐Constraint‐Induced Peroxide Activation for Electrophilic Reactivity
Authors: Chandra Anirban , Ansari Mursaleem , Monte‐Pérez Inés , Kundu Subrata , Rajaraman Gopalan , Ray Kallol
Published: April 2021

μ‐1,2‐peroxo‐bridged diiron(III) intermediates P are proposed as reactive intermediates in various biological oxidation reactions. In sMMO, P acts as an electrophile, and performs hydrogen atom and oxygen atom transfers to electron‐rich substrates. In cyanobacterial ADO, however, P is postulated to react by nucleophilic attack on electrophilic carbon atoms. In biomimetic studies, the ability of μ‐1,2‐peroxo‐bridged dimetal complexes of Fe, Co, Ni and Cu to act as nucleophiles that effect deformylation of aldehydes is documented. By performing reactivity and theoretical studies on an end‐on μ‐1,2‐peroxodicobalt(III) complex 1 involving a non‐heme ligand system, L1, supported on a Sn6O6 stannoxane core, we now show that a peroxo‐bridged dimetal complex can also be a reactive electrophile. The observed electrophilic chemistry, which is induced by the constraints provided by the Sn6O6 core, represents a new domain for metal−peroxide reactivity.
Ammonia Formation Catalyzed by a Dinitrogen‐Bridged Dirhenium Complex Bearing PNP‐Pincer Ligands under Mild Reaction Conditions**
Authors: Meng Fanqiang , Kuriyama Shogo , Tanaka Hiromasa , Egi Akihito , Yoshizawa Kazunari , Nishibayashi Yoshiaki
Published: April 2021

A series of rhenium complexes bearing a pyridine‐based PNP‐type pincer ligand are synthesized from rhenium phosphine complexes as precursors. A dinitrogen‐bridged dirhenium complex bearing the PNP‐type pincer ligands catalytically converts dinitrogen into ammonia during the reaction with KC8as a reductant and [HPCy3]BArF4(Cy=cyclohexyl, ArF=3,5‐(CF3)2C6H3) as a proton source at −78 °C to afford 8.4 equiv of ammonia based on the rhenium atom of the catalyst. The rhenium‐dinitrogen complex also catalyzes silylation of dinitrogen in the reaction with KC8as a reductant and Me3SiCl as a silylating reagent under ambient reaction conditions to afford 11.7 equiv of tris(trimethylsilyl)amine based on the rhenium atom of the catalyst. These results demonstrate the first successful example of catalytic nitrogen fixation under mild reaction conditions using rhenium‐dinitrogen complexes as catalysts.
Isolierung neutraler, mono‐ und dikationischer B2P2‐Ringe durch Addition eines Diphosphans an eine Bor‐Bor‐Dreifachbindung
Authors: Brückner Tobias , Fantuzzi Felipe , Stennett Tom E. , Krummenacher Ivo , Dewhurst Rian D. , Engels Bernd , Braunschweig Holger
Published: April 2021

Das NHC‐stabilisierte Diborin B2(SIDep)2 (SIDep=1,3‐Bis(2,6‐diethylphenyl)imidazolin‐2‐yliden) unterzieht sich bei Raumtemperatur einer P‐P‐Bindungsaktivierung mit Tetraethyldiphosphan, wobei mittels 1,2‐Diphosphinierung über ein Diphosphoryldiboren in hohen Ausbeuten B2P2‐Heterocyclen gebildet werden. In Abhängigkeit vom verwendeten Oxidationsmittel und Gegenion kann dieser Heterocyclus zu einem Radikalkation beziehungsweise Dikation oxidiert werden. Beginnend mit dem planaren, neutralen 1,3‐Bis(alkyliden)‐1,3‐diborata‐2,4‐diphosphoniocyclobutan führt jeder Oxidationsschritt zu einer verminderten B‐B‐Bindungslänge und dem Verlust der Planarität durch die Kationisierung. Röntgenstrukturanalysen in Kombination mit DFT‐ und CASSCF/NEVPT2‐Rechnungen offenbaren für die NHC‐stabilisierten dikationischen B2P2‐Ringe geschlossenschalige, schmetterlingsartige Strukturen, wovon die diradikaloiden Isomere mit planarem Ring in energetischer Nähe liegen.
Genetic Encoding and Enzymatic Deprotection of a Latent Thiol Side Chain to Enable New Protein Bioconjugation Applications
Authors: Reille‐Seroussi Marie , Meyer‐Ahrens Pascal , Aust Annika , Feldberg Anna‐Lena , Mootz Henning D.
Published: April 2021

The thiol group of the cysteine side chain is arguably the most versatile chemical handle in proteins. To expand the scope of established and commercially available thiol bioconjugation reagents, we genetically encoded a second such functional moiety in form of a latent thiol group that can be unmasked under mild physiological conditions. Phenylacetamidomethyl (Phacm) protected homocysteine (HcP) was incorporated and its latent thiol group unmasked on purified proteins using penicillin G acylase (PGA). The enzymatic deprotection depends on steric accessibility, but can occur efficiently within minutes on exposed positions in flexible sequences. The freshly liberated thiol group does not require treatment with reducing agents. We demonstrate the potential of this approach for protein modification with conceptually new schemes for regioselective dual labeling, thiol bioconjugation in presence of a preserved disulfide bond and formation of a novel intramolecular thioether crosslink.
Spatial Confinement Tunes Cleavage and Re‐Formation of C=N Bonds in Fluorescent Molecules
Authors: Liu Keyan , Qiao Xuezhi , Huang Chuanhui , Li Xiao , Xue Zhenjie , Wang Tie
Published: April 2021

Molecules in confined spaces exhibit unusual behaviors that are not typically observed in bulk systems. Such behavior can provide alternative strategies for exploring new reaction pathways. Cleavage of the C=N bond of Nile red (NR) in solution is an irreversible reaction. Here, we used spatial confinement within a cationic micelle‐confined system to convert this reaction to a reversible process. The fluorescence of NR shifted between red and green for nine cycles. The new chemical pathway based on spatial confinement can be attributed to two factors: increasing the local concentration of reactants and reducing the reaction energy barrier. This effect is supported by both experimental evidence and theoretical calculations. The cross‐linked silica shell comprising the confinement chamber stabilizes the enclosed molecules. This reduces fluorophore leakage and maintains fluorescence intensity in most environments, including in solution, on paper, and in hydrogel films, and expands practical applications in encrypted information and multi‐informational displays.
Enantio‐ und diastereoselektive, vollständige Hydrierung von Benzofuranen mittels Kaskadenkatalyse
Authors: Moock Daniel , Wagener Tobias , Hu Tianjiao , Gallagher Timothy , Glorius Frank
Published: April 2021

Wir berichten über eine enantio‐ und diastereoselektive, vollständige Hydrierung von mehrfach substituierten Benzofuranen in einer Eintopf‐Kaskadenkatalyse. Das entwickelte Protokoll ermöglicht den kontrollierten Aufbau von bis zu sechs definierten Stereozentren und erzeugt architektonisch komplexe Octahydrobenzofurane, die in vielen bioaktiven Molekülen vorkommen. Ein einzigartiges Zusammenspiel eines chiralen Ruthenium‐N‐heterozyklischen Carbenkomplexes und eines aus einem Komplexvorläufer in situ aktivierten Rhodiumkatalysators ermöglicht den vorgestellten Prozess.
Macrocyclic FKBP51 Ligands Define a Transient Binding Mode with Enhanced Selectivity
Authors: Voll Andreas M. , Meyners Christian , Taubert Martha C. , Bajaj Thomas , Heymann Tim , Merz Stephanie , Charalampidou Anna , Kolos Jürgen , Purder Patrick L. , Geiger Thomas M. , Wessig Pablo , Gassen Nils C. , Bracher Andreas , Hausch Felix
Published: April 2021

Subtype selectivity represents a challenge in many drug discovery campaigns. A typical example is the FK506 binding protein 51 (FKBP51), which has emerged as an attractive drug target. The most advanced FKBP51 ligands of the SAFit class are highly selective vs. FKBP52 but poorly discriminate against the homologs and off‐targets FKBP12 and FKBP12.6. During a macrocyclization pilot study, we observed that many of these macrocyclic analogs have unanticipated and unprecedented preference for FKBP51 over FKBP12 and FKBP12.6. Structural studies revealed that these macrocycles bind with a new binding mode featuring a transient conformation, which is disfavored for the small FKBPs. Using a conformation‐sensitive assay we show that this binding mode occurs in solution and is characteristic for this new class of compounds. The discovered macrocycles are non‐immunosuppressive, engage FKBP51 in cells, and block the cellular effect of FKBP51 on IKKα. Our findings provide a new chemical scaffold for improved FKBP51 ligands and the structural basis for enhanced selectivity.
Isolation of Neutral, Mono‐, and Dicationic B2P2 Rings by Diphosphorus Addition to a Boron−Boron Triple Bond
Authors: Brückner Tobias , Fantuzzi Felipe , Stennett Tom E. , Krummenacher Ivo , Dewhurst Rian D. , Engels Bernd , Braunschweig Holger
Published: April 2021

The NHC‐stabilised diboryne (B2(SIDep)2; SIDep=1,3‐bis(2,6‐diethylphenyl)imidazolin‐2‐ylidene) undergoes a high‐yielding P−P bond activation with tetraethyldiphosphine at room temperature to form a B2P2 heterocycle via a diphosphoryldiborene by 1,2‐diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3‐bis(alkylidene)‐1,3‐diborata‐2,4‐diphosphoniocyclobutane, each oxidation step leads to decreased B−B distances and loss of planarity by cationisation. X‐ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed‐shell singlet, butterfly‐shaped structures for the NHC‐stabilised dicationic B2P2 rings, with their diradicaloid, planar‐ring isomers lying close in energy.
Electro‐Conductive Single‐Molecule Magnet Composed of a Dysprosium(III)‐Phthalocyaninato Double‐Decker Complex with Magnetoresistance
Authors: Sato Tetsu , Breedlove Brian K. , Yamashita Masahiro , Katoh Keiichi
Published: April 2021

A one‐dimensional (1D) arrangement of an unsubstituted partially oxidized Dy3+ double‐decker complex, [DyPc2]Ix (Pc=phthalocyaninato, I=iodide; 1.93<x<2.26) (1), was obtained by using electro‐oxidation and chemical oxidation. In 1, the Pc ligands were partially oxidized, and I3− ion was present as a counter ion. From the results of spectrophotometric analysis on 1, the π radicals were delocalized in a 1D column and behaved as a conductor even at low‐temperatures. Since conductivity was observed at temperatures lower than the blocking temperature (TB), magnetoresistance (MR) effects corresponding to a magnetic hysteresis of single‐molecule magnet (SMM) were observed when the galvanomagnetic characteristics were investigated at 2.2 K.
A Light‐Operated Molecular Cable Car for Gated Ion Transport
Authors: Wang Chenxi , Wang Shunkang , Yang Huiting , Xiang Yanxin , Wang Xuebin , Bao Chunyan , Zhu Linyong , Tian He , Qu Da‐Hui
Published: April 2021

Inspired by the nontrivial and controlled movements of molecular machines, we report an azobenzene‐based molecular shuttle PR2, which can perform light‐gated ion transport across lipid membranes. The amphiphilicity and membrane‐spanning molecular length enable PR2 to insert into the bilayer membrane and efficiently transport K+ (EC50=4.1 μm) through the thermally driven stochastic shuttle motion of the crown ether ring along the axle. The significant difference in shuttling rate between trans‐PR2 and cis‐PR2 induced by molecular isomerization enables a light‐gated ion transport, i.e., ON/OFF in situ regulation of transport activity and single‐channel current. This work represents an example of using a photoswitchable molecular machine to realize gated ion transport, which demonstrates the value of molecular machines functioning in biomembranes.
Adducts of the Parent Boraphosphaketene H2BPCO and their Decarbonylative Insertion Chemistry
Authors: Hagspiel Stephan , Fantuzzi Felipe , Dewhurst Rian D. , Gärtner Annalena , Lindl Felix , Lamprecht Anna , Braunschweig Holger
Published: April 2021

The first examples of Lewis base adducts of the parent boraphosphaketene (H2B‐PCO) and their cyclodimers are prepared. One of these adducts is shown to undergo mild decarbonylation and phosphinidene insertion into a B−C bond of a borole, forming very rare examples of 1,2‐phosphaborinines, B/P isosteres of benzene. The strong donor properties of these 1,2‐phosphaborinines are confirmed by the synthesis of their π complexes with the Group 6 metals.
Chiral Metal Nanoparticle Superlattices Enabled by Porphyrin‐Based Supramolecular Structures
Authors: Yang Fei , Liu Xinyong , Yang Zhijie
Published: April 2021

Herein, we show that chiral metal nanoparticle superlattices can be produced through coassembly of achiral metal nanoparticles and porphyrin‐based organic molecules. This chirality transfer from molecules to nanoparticle superstructures across three orders of magnitude in length scale is enabled by the hetero chain‐chain van der Waals interactions. As far as we know, these are the first chiral nanoparticle assemblies based on chirality transfer through weak van der Waals forces. The dimensionality of the nanoparticle superlattices (1D chiral chains, 2D chiral sheets (cones), and 3D chiral particles) can be controlled based on a same synthetic chiral porphyrin molecule. Metalation of these porphyrin molecules with zinc cations results in the switching of molecular packing from J‐type to H‐type, which thereby produces 1D chiral nanoparticle chains. Functionalization of these zinc porphyrins with oleylamine can induce the assembly of nanoparticles into 2D chiral nanoparticle sheets.
Atomic Sulfur Filling Oxygen Vacancies Optimizes H Absorption and Boosts the Hydrogen Evolution Reaction in Alkaline Media
Authors: Jin Jing , Yin Jie , Liu Hongbo , Huang Bolong , Hu Yang , Zhang Hong , Sun Mingzi , Peng Yong , Xi Pinxian , Yan Chun‐Hua
Published: April 2021

The hydrogen evolution reaction (HER) usually has sluggish kinetics in alkaline solution due to the difficulty in forming binding protons. Herein we report an electrocatalyst in which sulfur atoms are doping in the oxygen vacancies (VO) of inverse spinel NiFe2O4 (S‐NiFe2O4) to create active sites with enhanced electron transfer capability. This electrocatalyst has an ultralow overpotential of 61 mV at the current density of 10 mA cm−2 and long‐term stability of 60 h at 1.0 Acm−2 in 1.0 M KOH media. In situ Raman spectroscopy revealed that S sites adsorb hydrogen adatom (H*) and in situ form S‐H*, which favor the production of hydrogen and boosts HER in alkaline solution. DFT calculations further verified that S introduction lowered the energy barrier of H2O dissociation. Both experimental and theoretical investigations confirmed S atoms are active sites of the S‐NiFe2O4.
Synthesis of Ionic Vinylene‐Linked Covalent Organic Frameworks through Quaternization‐Activated Knoevenagel Condensation
Authors: Meng Fancheng , Bi Shuai , Sun Zuobang , Jiang Biao , Wu Dongqing , Chen Jie‐Sheng , Zhang Fan
Published: April 2021

We developed a simple approach to synthesizing ionic vinylene‐linked two‐dimensional covalent organic frameworks (COFs) through a quaternization‐promoted Knoevenagel condensation at three aromatic methyl carbon atoms ofN‐ethyl‐2,4,6‐trimethylpyridinium halide with multitopic aromatic aldehyde derivatives. The resultant COFs exhibited a honeycomb‐like structure with high crystallinity and surface areas as large as 1343 m2 g−1. The regular shape‐persistent nanochannels and the positively charged polymeric frameworks allowed the COFs to be uniformly composited with linear polyethylene oxide and lithium salt, displaying ionic conductivity as high as 2.72×10−3 S cm−1.
Reconstructing tooth crown heights and enamel caps: A comparative test of three existing methods with recommendations for their use
Authors: O'Hara Mackie C. , Guatelli‐Steinberg Debbie
Published: April 2021

Studies of enamel growth and thickness, whether in paleoanthropology, bioarchaeology, or primatology, require measurements of crown height (CH), cuspal enamel thickness (CET), average (AET), and/or regional enamel thickness (RegAET) on complete, unworn crowns. Yet because fully unworn crowns are uncommon, three methods to bolster sample sizes by reconstructing slightly worn teeth have been developed: Profile, Polynomial, and Pen Tool. Although these methods have been tested for accuracy, no study has yet directly compared the three methods to assess their performance across CH, CET, AET, and RegAET measurements. Moreover, it is currently unclear how accurate the methods are when reconstructing crowns with varying degrees of wear. The present study addresses this gap in our understanding of how these methods perform on four key dental measurements, evaluates the degree of wear for which accurate crown reconstructions can be completed, and offers recommendations for applying these methods. Here, the methods are compared on Paranthropus robustus mandibular molars, a sample chosen because it exhibits variable morphology, presenting a challenge for reconstruction methods. For minimally worn teeth, Profile, Polynomial, and Pen Tool methods can be employed (in that order) for all measurements except CET, which cannot be reliably measured on reconstructions. For teeth with wear that obliterates the nadir of the occlusal basin or dentin horns, CH and AET can be measured using Profile and Polynomial reconstructions; however, no other measurements or methods were reliable. Recommendations provided here will make it possible to increase sample sizes and replicability, enhancing studies of enamel thickness and growth.
Effect of Atorvastatin on Knee Cartilage Volume in Patients With Symptomatic Knee Osteoarthritis: Results From a Randomized Placebo‐Controlled Trial
Authors: Wang Yuanyuan , Jones Graeme , Hill Catherine , Wluka Anita E. , Forbes Andrew B. , Tonkin Andrew , Hussain Sultana Monira , Ding Changhai , Cicuttini Flavia M.
Published: April 2021

Objective

To determine whether atorvastatin slows tibial cartilage volume loss in patients with symptomatic knee osteoarthritis (OA) in a multicenter, randomized, double‐blind, placebo‐controlled trial.

Methods

Participants ages 40–70 years were randomized to receive oral atorvastatin (40 mg once daily) (n = 151) or matching placebo (n = 153). The primary end point was annual percentage change in tibial cartilage volume over 2 years, assessed using magnetic resonance imaging (MRI). The prespecified secondary end points were progression of cartilage defects and bone marrow lesions over 2 years, which were assessed using MRI and change in Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index pain, stiffness, and function scores.

Results

A total of 248 of 304 participants (81.6%) completed the trial (mean age 55.7 years; 55.6% women). The annual change in tibial cartilage volume differed minimally between the atorvastatin and placebo groups (mean change –1.66% versus –2.17%, between‐group difference 0.50% [95% confidence interval (95% CI) –0.17%, 1.17%]). There were no significant differences in the progression of cartilage defects (odds ratio [OR] 0.86 [95% CI 0.52, 1.41]) or progression of bone marrow lesions (OR 1.00 [95% CI 0.62, 1.63]). Moreover, there were no significant differences in change in WOMAC pain, stiffness, or function scores over 2 years between the atorvastatin and placebo groups (mean change in pain score –36.0 versus –29.5, adjusted difference –2.7 [95% CI –27.1, 21.7]; mean change in stiffness score –14.2 versus –11.8, adjusted difference –0.2 [95% CI –12.2, 11.8]; mean change in function score –89.4 versus –87.5, adjusted difference 0.3 [95% CI –83.1, 83.6]). The incidence of adverse events (AEs) was similar between the atorvastatin and placebo groups (57 [37.7%] versus 52 [34.0%] experiencing AEs).

Conclusion

Treatment with oral atorvastatin (40 mg once daily), compared to placebo, did not significantly reduce cartilage volume loss over 2 years in patients with symptomatic knee OA. These findings do not support the use of atorvastatin for the treatment of knee OA.