scholarly journals Revealing the formation mechanism and band gap tuning of Sb2S3 nanoparticles

2021 ◽  
Author(s):  
Maximilian Joschko ◽  
Franck Yvan Fotue Wafo ◽  
Christina Malsi ◽  
Danilo Kisić ◽  
Ivana Validžić ◽  
...  

Sb2S3 is a promising nanomaterial for application in solar cells and other fields of electronics and optoelectronics. Sb2S3 nanoparticles were prepared via the hot-injection approach. In contrast to earlier work, the reaction temperature was decreased to 150°C, so that the reaction was slowed down and could be stopped at defined reaction stages. Thereby, the formation mechanism of the nanomaterial and the associated kinetics could be revealed. Based on morphological and structural analysis, it is suggested that seed particles (type 0) form immediately after injecting the antimony precursor into the sulfur precursor. These seeds fuse to form amorphous nanoparticles (type I) that contain a lower percentage of sulfur than that corresponding to the expected stoichiometric ratio of Sb2S3. The reason for this possibly lies in the formation of an oxygen- or carbon-containing intermediate during the seeding process. Afterward, the type I nanoparticles aggregate into larger amorphous nanoparticles (type II) in a second hierarchical assembly process and form superordinated structures (type III). This process is followed by the crystallization of these particles and a layer-like growth of the crystalline particles by an Ostwald ripening process at the expense of the amorphous particles. It was demonstrated that the kinetic control of the reaction allows tuning of the optical bandgap of the amorphous nanoparticles in the range of 2.2 – 2.0 eV. On the contrary, the optical bandgap of the crystalline particles decreases to a value of 1.7 eV and remains constant when the reaction progresses. Based on the proposed formation mechanism, future syntheses for Sb2S3 particles can be developed, allowing tuning the particles' properties in a broad range. In this way, the selective use of this material in a wide range of applications will become possible.

2021 ◽  
Vol 12 ◽  
pp. 1021-1033 ◽  
Author(s):  
Maximilian Joschko ◽  
Franck Yvan Fotue Wafo ◽  
Christina Malsi ◽  
Danilo Kisić ◽  
Ivana Validžić ◽  
...  

Sb2S3 is a promising nanomaterial for application in solar cells and in the fields of electronics and optoelectronics. Herein, Sb2S3 nanoparticles were prepared via the hot-injection approach. In contrast to earlier work, the reaction temperature was decreased to 150 °C so that the reaction was slowed down and could be stopped at defined reaction stages. Thereby, the formation mechanism of the nanomaterial and the associated kinetics could be revealed. Based on morphological and structural analyses, it is suggested that seed particles (type 0) formed immediately after injecting the antimony precursor into the sulfur precursor. These seeds fused to form amorphous nanoparticles (type I) that contained a lower percentage of sulfur than that corresponding to the expected stoichiometric ratio of Sb2S3. The reason for this possibly lies in the formation of an oxygen- or carbon-containing intermediate during the seeding process. Afterward, the type I nanoparticles aggregated into larger amorphous nanoparticles (type II) in a second hierarchical assembly process and formed superordinate structures (type III). This process was followed by the crystallization of these particles and a layer-like growth of the crystalline particles by an Ostwald ripening process at the expense of the amorphous particles. It was demonstrated that the kinetic control of the reaction allowed tuning of the optical band gap of the amorphous nanoparticles in the range of 2.2–2.0 eV. On the contrary, the optical band gap of the crystalline particles decreased to a value of 1.7 eV and remained constant when the reaction progressed. Based on the proposed formation mechanism, future syntheses for Sb2S3 particles can be developed, allowing tuning of the particle properties in a broad range. In this way, the selective use of this material in a wide range of applications will become possible.


Author(s):  
А.Р. Зарипова ◽  
Л.Р. Нургалиева ◽  
А.В. Тюрин ◽  
И.Р. Минниахметов ◽  
Р.И. Хусаинова

Проведено исследование гена интерферон индуцированного трансмембранного белка 5 (IFITM5) у 99 пациентов с несовершенным остеогенезом (НО) из 86 неродственных семей. НО - клинически и генетически гетерогенное наследственное заболевание соединительной ткани, основное клиническое проявление которого - множественные переломы, начиная с неонатального периода жизни, зачастую приводящие к инвалидизации с детского возраста. К основным клиническим признакам НО относятся голубые склеры, потеря слуха, аномалия дентина, повышенная ломкость костей, нарушения роста и осанки с развитием характерных инвалидизирующих деформаций костей и сопутствующих проблем, включающих дыхательные, неврологические, сердечные, почечные нарушения. НО встречается как у мужчин, так и у женщин. До сих пор не определена степень генетической гетерогенности заболевания. На сегодняшний день известно 20 генов, вовлеченных в патогенез НО, и исследователи разных стран продолжают искать новые гены. В последнее десятилетие стало известно, что аутосомно-рецессивные, аутосомно-доминантные и Х-сцепленные мутации в широком спектре генов, кодирующих белки, которые участвуют в синтезе коллагена I типа, его процессинге, секреции и посттрансляционной модификации, а также в белках, которые регулируют дифференцировку и активность костеобразующих клеток, вызывают НО. Мутации в гене IFITM5, также называемом BRIL (bone-restricted IFITM-like protein), участвующем в формировании остеобластов, приводят к развитию НО типа V. До 5% пациентов имеют НО типа V, который характеризуется образованием гиперпластического каллуса после переломов, кальцификацией межкостной мембраны предплечья и сетчатым рисунком ламелирования, наблюдаемого при гистологическом исследовании кости. В 2012 г. гетерозиготная мутация (c.-14C> T) в 5’-нетранслируемой области (UTR) гена IFITM5 была идентифицирована как основная причина НО V типа. В представленной работе проведен анализ гена IFITM5 и идентифицирована мутация c.-14C>T, возникшая de novo, у одного пациента с НО, которому впоследствии был установлен V тип заболевания. Также выявлены три известных полиморфных варианта: rs57285449; c.80G>C (p.Gly27Ala) и rs2293745; c.187-45C>T и rs755971385 c.279G>A (p.Thr93=) и один ранее не описанный вариант: c.128G>A (p.Ser43Asn) AGC>AAC (S/D), которые не являются патогенными. В статье уделяется внимание особенностям клинических проявлений НО V типа и рекомендуется определение мутации c.-14C>T в гене IFITM5 при подозрении на данную форму заболевания. A study was made of interferon-induced transmembrane protein 5 gene (IFITM5) in 99 patients with osteogenesis imperfecta (OI) from 86 unrelated families and a search for pathogenic gene variants involved in the formation of the disease phenotype. OI is a clinically and genetically heterogeneous hereditary disease of the connective tissue, the main clinical manifestation of which is multiple fractures, starting from the natal period of life, often leading to disability from childhood. The main clinical signs of OI include blue sclera, hearing loss, anomaly of dentin, increased fragility of bones, impaired growth and posture, with the development of characteristic disabling bone deformities and associated problems, including respiratory, neurological, cardiac, and renal disorders. OI occurs in both men and women. The degree of genetic heterogeneity of the disease has not yet been determined. To date, 20 genes are known to be involved in the pathogenesis of OI, and researchers from different countries continue to search for new genes. In the last decade, it has become known that autosomal recessive, autosomal dominant and X-linked mutations in a wide range of genes encoding proteins that are involved in the synthesis of type I collagen, its processing, secretion and post-translational modification, as well as in proteins that regulate the differentiation and activity of bone-forming cells cause OI. Mutations in the IFITM5 gene, also called BRIL (bone-restricted IFITM-like protein), involved in the formation of osteoblasts, lead to the development of OI type V. Up to 5% of patients have OI type V, which is characterized by the formation of a hyperplastic callus after fractures, calcification of the interosseous membrane of the forearm, and a mesh lamellar pattern observed during histological examination of the bone. In 2012, a heterozygous mutation (c.-14C> T) in the 5’-untranslated region (UTR) of the IFITM5 gene was identified as the main cause of OI type V. In the present work, the IFITM5 gene was analyzed and the de novo c.-14C> T mutation was identified in one patient with OI who was subsequently diagnosed with type V of the disease. Three known polymorphic variants were also identified: rs57285449; c.80G> C (p.Gly27Ala) and rs2293745; c.187-45C> T and rs755971385 c.279G> A (p.Thr93 =) and one previously undescribed variant: c.128G> A (p.Ser43Asn) AGC> AAC (S / D), which were not pathogenic. The article focuses on the features of the clinical manifestations of OI type V, and it is recommended to determine the c.-14C> T mutation in the IFITM5 gene if this form of the disease is suspected.


2020 ◽  
Vol 20 (12) ◽  
pp. 1074-1092 ◽  
Author(s):  
Rammohan R.Y. Bheemanaboina

Phosphoinositide 3-kinases (PI3Ks) are a family of ubiquitously distributed lipid kinases that control a wide variety of intracellular signaling pathways. Over the years, PI3K has emerged as an attractive target for the development of novel pharmaceuticals to treat cancer and various other diseases. In the last five years, four of the PI3K inhibitors viz. Idelalisib, Copanlisib, Duvelisib, and Alpelisib were approved by the FDA for the treatment of different types of cancer and several other PI3K inhibitors are currently under active clinical development. So far clinical candidates are non-selective kinase inhibitors with various off-target liabilities due to cross-reactivities. Hence, there is a need for the discovery of isoform-selective inhibitors with improved efficacy and fewer side-effects. The development of isoform-selective inhibitors is essential to reveal the unique functions of each isoform and its corresponding therapeutic potential. Although the clinical effect and relative benefit of pan and isoformselective inhibition will ultimately be determined, with the development of drug resistance and the demand for next-generation inhibitors, it will continue to be of great significance to understand the potential mechanism of isoform-selectivity. Because of the important role of type I PI3K family members in various pathophysiological processes, isoform-selective PI3K inhibitors may ultimately have considerable efficacy in a wide range of human diseases. This review summarizes the progress of isoformselective PI3K inhibitors in preclinical and early clinical studies for anticancer and other various diseases.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alfredo Sierra-Cristancho ◽  
Luis González-Osuna ◽  
Daniela Poblete ◽  
Emilio A. Cafferata ◽  
Paola Carvajal ◽  
...  

AbstractThis study aimed to analyze the root anatomy and root canal system morphology of mandibular first premolars in a Chilean population. 186 teeth were scanned using micro-computed tomography and reconstructed three-dimensionally. The root canal system morphology was classified using both Vertucci’s and Ahmed’s criteria. The radicular grooves were categorized using the ASUDAS system, and the presence of Tomes’ anomalous root was associated with Ahmed’s score. A single root canal was identified in 65.05% of teeth, being configuration type I according to Vertucci’s criteria and code 1MP1 according to Ahmed’s criteria. Radicular grooves were observed in 39.25% of teeth. The ASUDAS scores for radicular grooves were 60.75%, 13.98%, 12.36%, 10.22%, 2.15%, and 0.54%, from grade 0 to grade 5, respectively. The presence of Tomes’ anomalous root was identified only in teeth with multiple root canals, and it was more frequently associated with code 1MP1–2 of Ahmed’s criteria. The root canal system morphology of mandibular first premolars showed a wide range of anatomical variations in the Chilean population. Teeth with multiple root canals had a higher incidence of radicular grooves, which were closely related to more complex internal anatomy. Only teeth with multiple root canals presented Tomes’ anomalous root.


2015 ◽  
Vol 59 (6) ◽  
pp. 3066-3074 ◽  
Author(s):  
Arryn Craney ◽  
Floyd E. Romesberg

ABSTRACTAntibiotic-resistant bacteria are a significant public health concern and motivate efforts to develop new classes of antibiotics. One such class of antibiotics is the arylomycins, which target type I signal peptidase (SPase), the enzyme responsible for the release of secreted proteins from their N-terminal leader sequences. Despite the essentiality, conservation, and relative accessibility of SPase, the activity of the arylomycins is limited against some bacteria, including the important human pathogenStaphylococcus aureus. To understand the origins of the limited activity againstS. aureus, we characterized the susceptibility of a panel of strains to two arylomycin derivatives, arylomycin A-C16and its more potent analog arylomycin M131. We observed a wide range of susceptibilities to the two arylomycins and found that resistant strains were sensitized by cotreatment with tunicamycin, which inhibits the first step of wall teichoic acid synthesis. To further understand howS. aureusresponds to the arylomycins, we profiled the transcriptional response ofS. aureusNCTC 8325 to growth-inhibitory concentrations of arylomycin M131 and found that it upregulates the cell wall stress stimulon (CWSS) and an operon consisting of a putative transcriptional regulator and three hypothetical proteins. Interestingly, we found that mutations in the putative transcriptional regulator are correlated with resistance, and selection for resistanceex vivodemonstrated that mutations in this gene are sufficient for resistance. The results begin to elucidate howS. aureuscopes with secretion stress and how it evolves resistance to the inhibition of SPase.


2007 ◽  
Vol 76 (2) ◽  
pp. 704-716 ◽  
Author(s):  
Yih-Ling Tzeng ◽  
Charlene M. Kahler ◽  
Xinjian Zhang ◽  
David S. Stephens

ABSTRACT Two-component regulatory systems are involved in processes important for bacterial pathogenesis. Inactivation of the misR/misS system in Neisseria meningitidis results in the loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. One hundred seventeen (78 up-regulated and 39 down-regulated) potential regulatory targets of the MisR/MisS (MisR/S) system were identified by transcriptional profiling of the NMBmisR mutant and the parental wild-type meningococcal strain NMB. The regulatory effect was further confirmed in a subset of target genes by quantitative real-time PCR and β-galactosidase transcriptional fusion reporter assays. The MisR regulon includes genes encoding proteins necessary for protein folding in the bacterial cytoplasm and periplasm, transcriptional regulation, metabolism, iron assimilation, and type I protein transport. Mutation in the MisR/S system caused increased sensitivity to oxidative stress and also resulted in decreased susceptibility to complement-mediated killing by normal human serum. To identify the direct targets of MisR regulation, electrophoretic mobility shift assays were carried out using purified MisR-His6 protein. Among 22 genes examined, misR directly interacted with 14 promoter regions. Six promoters were further investigated by DNase I protection assays, and a MisR-binding consensus sequence was proposed. Thus, the direct regulatory targets of MisR and the minimal regulon of the meningococcal MisR/S two-component signal transduction system were characterized. These data indicate that the MisR/S system influences a wide range of biological functions in N. meningitidis either directly or via intermediate regulators.


CNS Spectrums ◽  
2009 ◽  
Vol 14 (8) ◽  
pp. 419-425 ◽  
Author(s):  
Mario Clerici ◽  
Beatrice Arosio ◽  
Emanuela Mundo ◽  
Elisabetta Cattaneo ◽  
Sara Pozzoli ◽  
...  

ABSTRACTIntroduction: An increasing amount of data suggests that dysregulation of the immune system, including the cytokine network, is associated with the etiology and pathophysiology of mood disorders. Genes encoding cytokines are highly polymorphic and single nucleotide polymorphisms, associated with increased or reduced cytokine production, have been described. The aim of this study was to define the genetic immunologic scenario associated with major depressive disorder (MDD) and bipolar disorder.Methods: Eighty-four Italian outpatients affected by bipolar disorder type I, bipolar disorder type II, or MDD, and 363 healthy controls were enrolled into the study. We analyzed allele and genotype distribution of −308 (G/A) tumor necrosis factor-α (TNF-α), +874 (T/A) interferon-γ (IFN-γ), -174 (G/C) interleukin (IL)-6, and −1082 (G/A) IL-10 promoter polymorphisms by Polymerase Chain Reaction Sequence Specific Primers technique.Results: We observed different genotype and allele distributions of TNF-α, IFN-γ, and IL-10 polymorphisms in the three groups of patients analyzed. In particular, bipolar II patients were characterized by an absence of adenine (A) high producer allele of TNF-α (P<.001) and a lower percentage of TT high producer genotype of IFN-γ (P <.001); bipolar I individuals showed reduced percentage of AA low producer genotype of IL-10 (P<.001). Both bipolar I and bipolar II patients not carrying guanine (G) high producer IL-6 allele showed a lower mean age at onset (P=.048).Conclusion: These data support the existence of a genetic profile related to pro-inflammatory cytokines in patients affected by mood disorders. The differences observed across the three clinical phenotypes suggest the presence of different pathogenetic mechanisms involved in the susceptibility of phenotypically different mood disorders.


2021 ◽  
Author(s):  
Zhihai Sun ◽  
Jiaxi Liu ◽  
Ying Zhang ◽  
Ziyuan Li ◽  
Leyu Peng ◽  
...  

Abstract Van der Waals (VDW) heterostructures have attracted significant research interest due to their tunable interfacial properties and potential in a wide range of applications such as electronics, optoelectronic, and heterocatalysis. In this work, the impact of interfacial defects on the electronic structures and photocatalytic properties of hBN/MX2(M = Mo, W, and X = S, Se) are studied using density functional theory calculations. The results reveal that the band alignment of hBN/MX2 can be adjusted by introducing vacancies and atomic doping. The type-I band alignment of the host structure was maintained in the heterostructure with n-type doping in the hBN sublayer. Interestingly, the band alignment changed to the type-II heterostructrue as VB defect and p-type doping was introduced in the hBN sublayer. This could be profitable for the separation of photo-generated electron−hole pairs at the interfaces and is highly desired for heterostructure photocatalysis. In addition, two Z-type heterostructures including hBN(BeB)/MoS2, hBN(BeB)/MoSe2, and hBN(VN)/MoSe2 were achieved, showing reducing band gap and ideal redox potential for water splitting. Our results reveal the possibility of engineering the interfacial and photocatalysis properties of hBN/MX2 heterostructures via interfacial defects.


1970 ◽  
Vol 29 (2) ◽  
pp. 78-84
Author(s):  
FH Chowdhury ◽  
MR Haque ◽  
NKSM Chowdhury ◽  
MS Islam ◽  
Z Raihan ◽  
...  

Cranio vertebral (CV) junction is one of the critical sites for surgery. It's anatomy, physiological aspects and pathological involvement varies in a wide range of margins. Common problems are developmental anomalies, traumatic involvement, inflammatory, infective and neoplastic lesion. Management of these problems varies a lot from each other. Aim of the article is to overview the pathologies in this area and to study presentations, investigations, surgical procedures and results of these pathologies. We prospectively analyzed 32 cases of Cranio-vertebral (CV) region surgery in the Department of Neurosurgery Dhaka Medical College Hospital and Mitford Hospital, Dhaka, from 2000 to 2008. In our series, male and female ratio was 7.2:1. Pathologies were atlanto- axial dislocation (AAD), Chiari malformation type –I, schwannoma, meningioma, hydatid cyst and tuberculosis. Common clinical findings were- neck pain, quadriparesis, quadriplegia, hand atrophy, autonomic dysfunction and hypertension. Various types of surgical procedures were done in this series according to the pathology. Death was in 01 case, neurological deterioration seen in one case, 2 cases were neurologically stable and 28 cases (87.5%) improved neurologically where one was non useful improvement (Frankel grade-C). Complete pre operative radiological study is a very important adjunct for a successful surgical result. Proper evaluation of patients with selection of appropriate surgical procedures along with safe surgical techniques are the necessary things for successful surgery in this area. DOI: http://dx.doi.org/10.3329/jbcps.v29i2.7952 (J Bangladesh Coll Phys Surg 2011; 29: 78-84)


2003 ◽  
Vol 89 (6) ◽  
pp. 3070-3082 ◽  
Author(s):  
Jason S. Rothman ◽  
Paul B. Manis

In the ventral cochlear nucleus (VCN), neurons transform information from auditory nerve fibers into a set of parallel ascending pathways, each emphasizing different aspects of the acoustic environment. Previous studies have shown that VCN neurons differ in their intrinsic electrical properties, including the K+ currents they express. In this study, we examine these K+ currents in more detail using whole cell voltage-clamp techniques on isolated VCN cells from adult guinea pigs at 22°C. Our results show a differential expression of three distinct K+ currents. Whereas some VCN cells express only a high-threshold delayed-rectifier-like current ( IHT), others express IHT in combination with a fast inactivating current ( IA) and/or a slow-inactivating low-threshold current ( ILT). IHT, ILT, and IA, were partially blocked by 1 mM 4-aminopyridine. In contrast, only ILT was blocked by 10–100 nM dendrotoxin-I. A surprising finding was the wide range of levels of ILT, suggesting ILT is expressed as a continuum across cell types rather than modally in a particular cell type. IA, on the other hand, appears to be expressed only in cells that show little or no ILT, the Type I cells. Boltzmann analysis shows IHT activates with 164 ± 12 (SE) nS peak conductance, -14.3 ± 0.7 mV half-activation, and 7.0 ± 0.5 mV slope factor. Similar analysis shows ILT activates with 171 ± 22 nS peak conductance, -47.4 ± 1.0 mV half-activation, and 5.8 ± 0.3 mV slope factor.


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