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1.
Indian J Otolaryngol Head Neck Surg ; 76(2): 2134-2136, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38566643

RESUMO

Giant Cell Tumors of the skull are rare and mostly occur in the middle cranial fossa. Radiological investigations serve as adjunct modalities; however, histopathological confirmation is mandatory. Ten to forty% of GCTs may be recurrent. Complete surgical resection is the treatment of choice, however, partial resection with adjuvant radiotherapy can serve as a secondary alternative. Recurrent cases require post-op radiotherapy. Here, we describe a case of recurrent giant cell tumor of sphenoid bone in a young male, who underwent surgical resection twice, after which he was advised adjuvant radiotherapy and denosumab. The patient did not take radiotherapy.

2.
Clin Case Rep ; 12(4): e8759, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38617069

RESUMO

Key Clinical Message: Foreign body ingestion is common in pediatric age group however can be found in any age group with intellectual disability and neurodevelopmental delay. There is usually a delay in presentation and interventions following foreign body ingestion in patients with neurodevelopmental delay, leading to increased morbidity, mortality, and complications owing to inability of such patients giving relevant history. Most ingested foreign bodies naturally pass through the digestive tract without untoward effects. Only a few patients may require surgical interventions. Principle of management should be to reduce anxiety among patients and their visitors. Speedy recovery is enhanced so that they can return to their familiar environment soon. Abstract: Foreign body ingestion is common in pediatric populations and may be found in any age group with intellectual disability and neurodevelopmental delay. As the patient cannot give a clear and relevant history, there is usually a delay in presentation and interventions following foreign body ingestion in patients with neurodevelopmental delay, leading to increased morbidity, mortality, and complications. Most foreign bodies pass through the digestive system without any complications, and very few require surgical intervention. The goal should be to reduce anxiety among patients and their visitors and to enhance speedy recovery so that they can return to their familiar environment soon. Here we report a case of Acute intestinal obstruction secondary to ingestion of the head portion of a doll which was managed with emergency laparotomy with enterotomy and removal of foreign body in a 16 years female with Autism Spectrum Disorder.

4.
Neuropathology ; 2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38409890

RESUMO

Astroblastoma is an uncommon circumscribed glial tumor mostly involving the cerebral hemisphere. The characteristic molecular alteration is meningioma (disrupted in balanced translocation) 1 (MN1) rearrangement. No definite World Health Organization grade has been assigned as both low- and high-grade tumors are known to occur. Tumors in the spine are extremely rare; to date only three cases have been reported in the literature. A vigilant microscopy and ancillary testing aid in diagnosis when the tumors present in unusual locations, as in our case. The prompt differentiation of this tumor from its mimickers is a mandate as modalities of management are different and not clearly established.

5.
Radiol Case Rep ; 19(5): 1819-1822, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38420343

RESUMO

Blunt trauma abdomen with abdominal wall herniation with bowel perforation is an acute emergency condition. Road traffic accidents causing blunt trauma are common in a youngster like in our case. Once the patient is resuscitated, ultrasonography and Computed tomography must be done. Early surgical exploration with mesh or primary repair of the defect is the mainstay of management. We have a case of a 25-year-old male with blunt trauma abdomen and anterior wall hernia following a road traffic accident who was managed with emergency exploratory laparotomy as computed tomography suggested anterior abdominal wall herniation of bowel content.

6.
Reprod Biol ; 24(2): 100862, 2024 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-38402721

RESUMO

Calpain role has been shown in the cumulus cell-oocyte complexes and, corpus luteum. We investigated the association of calpains-1 and -2 in ovarian folliculogenesis using the Sprague-Dawley (SD) rat model and steroidogenesis in the human granulosa cells (hGCs). We induced PCOS in 42-day-old SD rats by letrozole oral gavage for 21 days. Premature ovarian failure (POF) was induced in 21-day-old SD rats by 4-vinylcyclohexene diepoxide (VCD). Ovulation and ovarian hyperstimulatory (OHS) syndrome were induced by pregnant mare gonadotropin (PMSG) + human chorionic gonadotropin (hCG) treatments in 21 days SD rats, respectively. Steroidogenesis is stimulated in human granulosa cells (hGCs) by forskolin and the response of 17-beta-estradiol (E2) on calpains expression was checked in hGCs. The protein expression by immunoblotting and activity by biochemical assay of calpains-1 and -2 showed an oscillating pattern in the ovarian cycle. PMSG-induced follicular recruitment showed upregulation of calpains-1 and -2, but with no change during ovarian function cessation (POF). Upregulated calpain-2 expression and calpain activity was found in the hCG +PMSG-induced ovulation. Letrozole-induced PCOS showed downregulation of calpain-1, but upregulation of calpain-2. PMSG+hCG-induced OHS led to the upregulation of calpain-1. Letrozole and metformin separately increased the expression level of calpains-1 and -2 in the hGCs during luteinization. In conclusion, the expression levels of calpains -1 and -2 are increased with ovarian follicular recruitment by PMSG and calpain-1 is decreased in the PCOS condition, and letrozole and metformin upregulate the expression of calpains-1 and -2 during luteinization in the hGCs possibly via E2 action.

7.
Radiol Case Rep ; 19(4): 1424-1431, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38292787

RESUMO

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors involving the gastrointestinal tract, arising from the interstitial cells of Cajal. GIST comprises about 1% of all GI tumors. Rectal GISTs are rare and comprise of approximately 5% of all GISTs and only 0.1% of rectal tumors are found to be GISTs. Rectal GISTs may be diagnosed incidentally or present with symptoms, including defecation problems, bleeding, and/or pain. We report a case of a 46-year-old male with rectal GIST metastasized to the liver and bilateral lung parenchyma managed by Imatinib Mesylate (IM) regimen. Rectal GIST although being rare, must be considered as a differential diagnosis in a patient presenting with defecatory problems with bleeding.

9.
Nano Lett ; 24(1): 458-465, 2024 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-38148139

RESUMO

The subvalent silver kernel represents the nascent state of silver cluster formation, yet the growth mechanism has long been elusive. Herein, two silver nanoclusters (Ag30 and Ag34) coprotected by TC4A4- (H4TC4A = p-tert-butylthiacalix[4]arene) and TBPMT- (TBPMTH = 4-tert-butylbenzenemethanethiol) containing 6e and 4e silver kernels are synthesized and characterized. The trimer of the 2e superatom Ag14 kernel in Ag30 is built from a central Ag6 octahedron sandwiched by two orthogonally oriented Ag5 trigonal bipyramids through sharing vertexes, whereas a double-octahedral Ag10 kernel in Ag34 is a dimer of 2e superatoms. They manifest disparate polyhedron fusion growth patterns at the beginning of the silver cluster formation. Their excellent solution stabilities are contributed by the multisite and multidentate coordination fashion of TC4A4- and the special valence electron structures. This work demonstrates the precise control of silver kernel growth by the solvent strategy and lays a foundation for silver nanocluster application in photothermal conversion.

10.
Curr Microbiol ; 81(1): 27, 2023 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-38041739

RESUMO

Multidrug-resistant tuberculosis (MDR-TB) requires treatment with fluoroquinolone (FLQ) drugs, however, the excessive use of FLQ has led to the rise of extensively drug-resistant TB. In 2019, ~ 20% of total MDR-TB cases were estimated to be resistant to FLQ drugs. In the present study, we developed and evaluated the utility of high-resolution melt curve analysis (HRM) for the rapid detection of FLQ-resistant Mycobacterium tuberculosis for the first time directly from sputum samples. A reference plasmid library was generated for the most frequently observed mutations of gyrA gene and was used to discriminate between mutant and wild-type samples in the FLQ-HRM assay. The developed assay was evaluated on n = 25 MDR M. tuberculosis clinical isolates followed by validation on archived sputum DNA (n = 88) using DNA sequencing as a gold standard. The FLQ-HRM assay showed a 100% sensitivity [95% Confidence Interval (CI): 71.5 to 100] and specificity (95% CI: 39.7 to 100) in smear-positive category, and a sensitivity of 88.9% (95% CI: 77.3 to 95.8) with 84.2% (95% CI: 60.4 to 96.6) specificity in smear-negative category. The assay showed a high level of concordance of ~ 90% (κ = 0.74) with DNA sequencing, however, we were limited by the absence of phenotypic drug susceptibility testing data. In conclusion, HRM is a rapid, cost-effective (INR 150/USD 1.83) and closed-tube method for direct detection of FLQ resistance in sputum samples including direct smear-negative samples.


Assuntos
Mycobacterium tuberculosis , Tuberculose Resistente a Múltiplos Medicamentos , Humanos , Antituberculosos/farmacologia , Isoniazida/farmacologia , Escarro/microbiologia , Rifampina/farmacologia , Fluoroquinolonas/farmacologia , Fluoroquinolonas/uso terapêutico , Testes de Sensibilidade Microbiana , Sensibilidade e Especificidade , Tuberculose Resistente a Múltiplos Medicamentos/diagnóstico , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Tuberculose Resistente a Múltiplos Medicamentos/microbiologia
11.
Int J Biol Macromol ; 253(Pt 2): 126772, 2023 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-37683744

RESUMO

The goal of the proposed study is to investigate the effects of three different power levels (30, 32 and 34 kV) and exposure time (2, 4 and 8 min) of dielectric barrier discharge (DBD) atmospheric cold plasma treatment on the functional and physicochemical characteristics of taro starch. Investigations were done into how different treatments impact the multi-structural, functional and physicochemical attributes of taro starch. The findings showed that cold plasma treatments substantially impacted starch granule shapes (3.60-2.54 µm), such as reduced aggregations and developed fissures on granule surface due to the generation of an etching by plasma species and enhancement in the surface topography and roughness of treated starch as compared with native by SEM and AFM analysis. Besides this, no variations were detected in the functional groups of taro starch using FT-IR analysis after cold plasma treatments. However, the A-type pattern in the XRD did not affect it, while a reduction in relative crystallinity (14.20-11.50 %) was seen as a function of the active plasma species depolymerization. Furthermore, depending on the cold plasma voltage and treatment time, amylose content (20.12-15.98 %), paste clarity (24.48-31.27 %), solubility (0.41-65.53 %), freezing thaw stability (% syneresis) (32.10-42.58 %), color properties (L*, 94.79-97.52), whiteness index (79.37-84.66), molecular weight distribution (Peak 1, 12.79-5.35 × 108 g/mol; Peak 2, 4.20-1.56 × 107 g/mol) and in vitro digestibility (RDS, 64.10-64.08 %) significantly changed. So, based on these excellent properties, this study suggested that cold plasm-treated taro starch can be used in the field of food packaging material, functional food and pharmaceutical products. Therefore, a potential approach for physically altering starch is plasma treatment.


Assuntos
Colocasia , Gases em Plasma , Amido/química , Colocasia/química , Gases em Plasma/química , Espectroscopia de Infravermelho com Transformada de Fourier , Amilose/química
12.
Pathogens ; 12(8)2023 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-37623956

RESUMO

Areca nut and slaked lime, with or without tobacco wrapped in Piper betle leaf, prepared as betel quid, is extensively consumed as a masticatory product in many countries across the world. Betel Quid can promote the malignant transformation of oral lesions as well as trigger benign cellular and molecular changes. In the oral cavity, it causes changes at the compositional level in oral microbiota called dysbiosis. This dysbiosis may play an important role in Oral Cancer in betel quid chewers. The abnormal presence and increase of bacteria Fusobacterium nucleatum, Capnocytophaga gingivalis, Prevotella melaninogenica, Peptostreptococcus sp., Porphyromonas gingivalis, and Streptococcus mitis in saliva and/or other oral sites of the cancer patients has attracted frequent attention for its association with oral cancer development. In the present review, the authors have analysed the literature reports to revisit the oncogenic potential of betel quid and oral microbiome alterations, evaluating the potential of oral microbiota both as a driver and biomarker of oral cancer. The authors have also shared a perspective that the restoration of local microbiota can become a potentially therapeutic or prophylactic strategy for the delay or reversal of lip and oral cavity cancers, especially in high-risk population groups.

13.
J Am Chem Soc ; 145(36): 19523-19532, 2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37646485

RESUMO

Structural transformation of metal nanoclusters (NCs) is of great ongoing interest regarding their synthesis, stability, and reactivity. Although sporadic examples of cluster transformations have been reported, neither the underlying transformation mechanism nor the intermediates are unambiguous. Herein, we have synthesized a flexible 54-nuclei silver cluster (Ag54) by combining soft (tBuC≡C-) and hard (nPrCOO-) ligands. The existence of weakly coordinated nPrCOO- enhances the reactivity of Ag54, thus facilitating the dicarboxylic acid to induce structural transformation. X-ray structural analyses reveal that Ag54 transforms to Ag28 cluster-based 2D networks (Ag28a and Ag28b) induced by H2suc (succinic acid) and H2glu (glutaric acid), whereas with H2pda (2,2'-(1,2-phenylene)diacetic acid), a discrete Ag28 cluster (Ag28c) is isolated. The key intermediate Ag17 that emerges during the self-dissociation of Ag54 was isolated by using cryogenic recrystallization and characterized by X-ray crystallography. The "tandem transformation" mechanism for the structure evolution from Ag54 to Ag28a is established by time-dependent electrospray ionization mass spectrometry (ESI-MS) and UV-vis spectroscopy. In addition, the catalytic activity in the 4-nitrophenol reduction follows the sequence Ag28c > Ag28b > Ag28a > Ag54 due to more bare silver sites on the surface of the Ag28 cluster unit. Our findings not only open new avenues to the synthesis of silver NCs but also shed light on a better understanding of the structural transformation mechanism from one cluster to another or cluster-based metal-organic networks induced by dicarboxylates.

14.
Natl Med J India ; 36(1): 36-39, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37615139

RESUMO

Background The medical curriculum for undergraduates was revised by the Medical Council of India in 2019, after 21 years. We did this study to determine teachers' pedagogical and technical readiness to implement the competency-based curriculum in medical colleges and determine factors that affect readiness, from their perspective. Methods We conducted a cross-sectional survey in the form of an online questionnaire. The qualitative data were coded numerically and were analysed using frequencies and proportions. Pearson Chi-square test was used to study the association among variables. Results The majority (85%) of respondents had attended a curriculum implementation training programme; 62.2% with experience <5 years, 56.1% with experience 5-10 years and a minority of 13.3% with >10 years' experience were ready to a 'great extent' to implement the new curriculum; 54.1% agreed to re-frame lectures and 64.9% possessed technological skills to suit the needs of a competency-based curriculum. About 77% agreed that it will provide a rich learning environment, inspire self-directed learning while 52% believed it will promote scientific thinking and provide better learning outcomes in the long run. Conclusion Medical teachers had a positive attitude towards implementation of the new curriculum. However, numerous factors such as low teacher-student ratio, textbooks designed according to the traditional curriculum, limited teachers' training and cumbersome paperwork may hinder its successful implementation. Updation of teachers' knowledge and skills through seminars/workshops is recommended to facilitate delivery of the new curriculum. Like any other ongoing reforms in medical education, competency-based curriculum is a work in process.


Assuntos
Educação Médica , Docentes de Medicina , Humanos , Estudos Transversais , Currículo , Aprendizagem
15.
Tuberculosis (Edinb) ; 142: 102369, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37536090

RESUMO

Pleural tuberculosis (pTB) is a grave clinical challenge. A novel cell-free M. tuberculosis DNA (cfM.tb-DNA) probe-based-qPCR assay was developed for the diagnosis of pTB. Total cell-free DNA was extracted from pleural fluid (PF) and paired plasma samples and cfM.tb-DNA was quantified by probe-based qPCR targeting devR (109-bp) gene of M. tuberculosis in patients with pleural effusion. Patient categorization was done using 'Composite-Reference-Standard' formulated for the study. Assay cut-offs were determined from samples in the 'Development set' (n = 17; 'Definite & Probable' pTB; n = 9 and 'Non-TB'; n = 8) by ROC-curve analysis and applied to 'Validation set' (n = 112; 'Definite' pTB; n = 8, 'Probable' pTB; n = 34, 'Possible' pTB; n = 28 and 'Non-TB'; n = 42). cfM.tb-DNA qPCR had a sensitivity of 62.5% (95%CI; 24.4,91.4) in 'Definite' pTB category and 59.5% (95%CI; 43.2,74.3) in 'Definite & Probable' pTB category with 95.2% (95%CI; 83.8,99.4) specificity using PF. In plasma (n = 85), the assay had a sub-optimal sensitivity of 7.6% (95%CI; 0.95,25.1) with 88.2% (95%CI; 72.5,96.7) specificity in 'Definite & Probable' pTB group. Xpert MTB/RIF assay detected only six-samples in the 'Validation set'. Logistic regression analysis indicated that PF-cfM.tb-DNA qPCR provided incremental advantage over existing pTB diagnostic algorithms. To the best of our knowledge, this is the first report describing the utility of cfM.tb-DNA for pTB diagnosis in India.


Assuntos
Ácidos Nucleicos Livres , Mycobacterium tuberculosis , Tuberculose Pleural , Humanos , Mycobacterium tuberculosis/genética , Tuberculose Pleural/diagnóstico , Tuberculose Pleural/microbiologia , Ácidos Nucleicos Livres/genética , Sensibilidade e Especificidade , Curva ROC
16.
J Food Sci Technol ; 60(8): 2105-2120, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37273559

RESUMO

Edible insects (EI) are also becoming as a part of the diet due to their nutritional value and health benefits in many regions of the world. These EI are inexhaustible sources accessible by garnering from the wild with high feed conversion efficiency. Appreciating the budding of EI in justifiable food production, enlightening food security and biodiversity conversion, is promising a sufficient supply of the insect resource for future food to the world. These insects are processed to develop new products, improve organoleptic and nutritional parameters as well as the extension of shelf life. In this review, we discuss the edible insect characteristics, the potential application of EI in food industry, processing, pretreatments, drying, extraction of edible compounds like protein, lipid and chitin various food products formulation, safety regulation. Availability of broad nutritional spectrum of EI includes protein, mono and poly unsaturaturated fatty acids, amino acids, vitamins, amino aids and minerals has been used as an ingredient in development of various forms of food products such as flours in the form of whole insect powder, protein isolate, canned products, extruded products, hard candies, spreads, liquor infusion, cookies and other products.

17.
Arch Microbiol ; 205(7): 270, 2023 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-37356030

RESUMO

Nitrogen metabolism in the genus Citrobacter is very poorly studied despite its several implications in wastewater treatment. In the current study, Citrobacter portucalensis strain AAK_AS5 was assessed for remediation of simulated wastewater supplemented with different inorganic nitrogen sources. Combination of (NH4)2SO4 with KNO3 was the most preferred for achieving high growth density followed by (NH4)2SO4 and KNO3 alone. This was in agreement with highest ammonical nitrogen removal of 92.9% in the presence of combined nitrogen sources and the corresponding nitrate nitrogen removal of 93% in the presence of KNO3. Furthermore, these removal capacities were validated by investigating the uniqueness and the spread of metabolic features through pan-genomic approach that revealed the largest number of unique genes (2097) and accessory genes (705) in strain AAK_AS5. Of the total 44 different types of nitrogen metabolism-related genes, 39 genes were associated with the core genome, while 5 genes such as gltI, nasA, nasR, nrtA, and ntrC uniquely belonged to the accessory genome. Strain AAK_AS5 possessed three major nitrate removal pathways viz., assimilatory and dissimilatory nitrate reduction to ammonia (ANRA & DNRA), and denitrification; however, the absence of nitrification was compensated by ammonia assimilation catalyzed by gene products of the GDH and GS-GOGAT pathways. narGHIJ encoding the respiratory nitrate reductase was commonly identified in all the studied genomes, while genes such as nirK, norB, and nosZ were uniquely present in the strain AAK_AS5 only. A markedly different genetic content and metabolic diversity between the strains reflected their adaptive evolution in the environment thus highlighting the significance of C. portucalensis AAK_AS5 for potential application in nitrogen removal from wastewater.


Assuntos
Desnitrificação , Águas Residuárias , Nitratos , Amônia , Nitrogênio/metabolismo , Nitrificação , Citrobacter/genética , Citrobacter/metabolismo , Processos Heterotróficos , Aerobiose , Nitritos/metabolismo
18.
Phytother Res ; 37(9): 4018-4041, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37165686

RESUMO

Polycystic ovary syndrome (PCOS) is most common in women of reproductive age, giving rise to androgen excess and anovulation, leading to infertility and non-reproductive complications. We explored the ameliorating effect of naringenin in PCOS using the Sprague Dawley (SD) rat model and human granulosa cells. Letrozole-induced PCOS rats were given either naringenin (50 mg/kg/day) alone or in combination with metformin (300 mg/kg/day), followed by the estrous cycle, hormonal analysis, and glucose sensitivity test. To evaluate the effect of naringenin on granulosa cell (hGC) steroidogenesis, we treated cells with naringenin (2.5 µM) alone or in combination with metformin (1 mM) in the presence of forskolin (10 µM). To determine the steroidogenesis of CYP-17A1, -19A1, and 3ßHSD2, the protein expression levels were examined. Treatment with naringenin in the PCOS animal groups increased ovulation potential and decreased cystic follicles and levels of androgens. The expression levels of CYP-17A1, -19A1, and 3ßHSD2, were seen restored in the ovary of PCOS SD rats' model and in the human ovarian cells in response to the naringenin. We found an increased expression level of phosphorylated-AKT in the ovary and hGCs by naringenin. Naringenin improves ovulation and suppress androgens and cystic follicles, involving AKT activation.


Assuntos
Cisto Folicular , Metformina , Síndrome do Ovário Policístico , Humanos , Feminino , Ratos , Animais , Androgênios/efeitos adversos , Ratos Sprague-Dawley , Letrozol/efeitos adversos , Proteínas Proto-Oncogênicas c-akt , Cisto Folicular/complicações , Modelos Animais de Doenças
19.
Reprod Biol ; 23(2): 100754, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-36934663

RESUMO

We investigated the role of protein kinase c (PKC) -α and -ß during the ovarian follicular dynamics using estrous cycle, gonadotropin-induced ovulation, and antral follicle culture, 4-vinylcyclohexene diepoxide (VCD)-induced premature ovarian failure (POF) in the SD rat models. We found the higher activity of PKC during the proestrus stage along with expression of PKC-α during the estrus and metestrus stages of the estrous cycle while PKC-ß expression was increased during the diestrus, proestrus, and estrus stages. In response to pregnant mare gonadotropin (PMSG)-induced follicular recruitment and ovulation, the phosphorylated (Thr-642) PKC-ß was increased. PKC activity inhibition by hispidin during the proestrus stage resulted in decreased antral follicles and corpus luteum. Treatment with hispidin resulted in the downregulation of granulosa cell (GC) biomarker, follicle stimulating hormone receptor (FSHR) expression in the cultured pre-antral follicle. During the forskolin-induced luteinization of human granulosa cells, the expression level of PKC-α and ß (I and II) was decreased. In the POF condition, the activity of total PKC and the expression levels of PKC-α and ß (I and II) were increased. Immunostaining depicted ubiquitous expression of PKC-α in the ovary during the estrous cycle and POF conditions. Taken together, we conclude the association of PKC-α and -ß (I and II) during ovarian follicular dynamics where the expression level of PKC-α is increased, but the expression level of PKC-ß (I and II) is suppressed in the POF condition in the SD rat model.


Assuntos
Insuficiência Ovariana Primária , Animais , Feminino , Ratos , Gonadotropinas/farmacologia , Proteína Quinase C beta , Ratos Sprague-Dawley
20.
Chem Sci ; 14(5): 1138-1144, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36756341

RESUMO

Precise control over the shape and size of metal nanoclusters through anion template-driven self-assembly is one of the key scientific goals in the nanocluster community, however, it is still not understood comprehensively. In this work, we report the controllable synthesis and atomically precise structures of silver nanowheels Ag37 and Ag46, using homo (Cl- ions) and heteroanion (Cl- and CrO4 2- ions) template strategies, along with macrocyclic p-phenyl-thiacalix[4]arene and small iPrS- ligands. Structural analyses revealed that in Ag37, Cl- ions serve as both local and global templates, whereas CrO4 2- ions function as local and Cl- ions as global templates in Ag46, resulting in a pentagonal nanowheel (Ag37) and a hexagonal (Ag46) nanowheel. The larger ionic size and more negative charges of CrO4 2- ions than Cl- ions offer more coordination sites for the silver atoms and are believed to be the key factors that drive the nanowheel core to expand significantly. Also, by taking advantage of the deep cavity of thiacalix[4]arene with an extended phenyl group, Ag46 has been used as a host material for dye adsorption depending on the charge and size of organic dyes. The successful use of heteroanions to control the expansion of well-defined silver nanowheels fills the knowledge gap in understanding the directing role of heteroanions in dictating the shape and size of nanoclusters at the atomic level.

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