Characterisation of chitin in the cuticle of a velvet worm (Onychophora)

*Kaya, Murat ( Aksaray, Yazar ) *Baran, Talat ( Aksaray, Yazar )We characterize the trunk cuticle of velvet worms of the Peripatoides novaezealandiae-group (Onychophora) using SEM, TEM, Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). TEM and SEM revealed a relatively uniform organization of the delicate cuticle that is covered by numerous bristled and nonbristled papillae with ribbed scales arranged in transverse rows. The cuticle consists of a very thin multilayered epicuticle of varying appearance followed by the largely fibrous procuticle. The irregularly arranged nanofibres of isolated cuticular chitin seen by SEM are considered as bundles of chitin fibres. FT-IR and TGA showed that the chitin is of the α-type. This confirms and broadens the single previous study in which the presence of α-chitin in a velvet worm was demonstrated with a single analysis (X-ray diffraction)...

BMPRII deficiency impairs apoptosis via the BMPRII-ALK1-BclX-mediated pathway in pulmonary arterial hypertension (PAH)

YesPulmonary Arterial Hypertension (PAH) is a devastating cardiovascular disorder characterised by the remodelling of pre-capillary pulmonary arteries. The vascular remodelling observed in PAH patients results from excessive proliferation and apoptosis resistance of pulmonary arterial smooth muscle (PASMCs) and endothelial cells (PAECs). We have previously demonstrated that mutations in the type II receptor for bone morphogenetic protein (BMPRII) underlie the majority of the familial and inherited forms of the disease. We have further demonstrated that BMPRII deficiency promotes excessive proliferation and attenuates apoptosis in PASMCs, but the underlying mechanisms remain unclear. The major objective of this study is to investigate how BMPRII deficiency impairs apoptosis in PAH. Using multidisciplinary approaches, we demonstrate that deficiency in the expression of BMPRII impairs apoptosis by modulating the alternative splicing of the apoptotic regulator, Bcl-x (B-cell lymphoma X) transcripts: a finding observed in circulating leukocytes and lungs of PAH subjects, hypoxia-induced PAH rat lungs as well as in PASMCs and PAECs. BMPRII deficiency elicits cell specific effects: promoting the expression of Bcl-xL transcripts in PASMCs whilst inhibiting it in ECs, thus exerting differential apoptotic effects in these cells. The pro-survival effect of BMPRII receptor is mediated through the activin receptor like kinase 1 (ALK1) but not the ALK3 receptor. Finally, we show that BMPRII interacts with the ALK1 receptor and pathogenic mutations in the BMPR2 gene abolish this interaction. Taken together, dysfunctional BMPRII responsiveness impairs apoptosis via the BMPRII-ALK1-Bcl-xL pathway in PAH. We suggest Bcl-xL as a potential biomarker and druggable target.This work was supported by a fellowship (awarded to MTN) from the Department of Health via the NIHR Comprehensive Biomedical Research Centre award to Guy’s & St Thomas’ NHS Foundation Trust in partnership with King’s College London, Heptagon Life Science Proof of Concept Fund (grant KCL24 to MTN), the Great Britain Sasakawa Foundation (grant B70 to MTN), the Royal Society (grant 43049 to MTN), the Medical Research Council (grant G900865 to RCT, MTN and NWM) and the University of Bradford (grants 003200, 66006/001NAS and DH005 to MTN). NS and MYB were supported by scholarships from the Commonwealth Scholarship Commission, UK and Scientific and Technological Research Council of Turkey (TUBITAK), respectively

Synthesis of a magnetic polystyrene-supported Cu(II)-containing heterocyclic complex as a magnetically separable and reusable catalyst for the preparation of N-sulfonyl-N-aryl tetrazoles

In this work, a cost-effective, environmentally friendly, and convenient method for synthesizing a novel heterogeneous catalyst via modification of polystyrene using tetrazole-copper magnetic complex [Ps@Tet-Cu(II)@Fe3O4] has been successfully developed. The synthesized complex was analyzed using TEM (transmission electron microscopy), HRTEM (high resolution-transmission electron microscopy), STEM (scanning transmission electron microscopy), FFT (Fast Fourier transform), XRD (X-ray diffraction), FT-IR (Fourier transform-infrared spectroscopy), TG/DTG (Thermogravimetry and differential thermogravimetry), ICP-OES (Inductively coupled plasma-optical emission spectrometry), Vibrating sample magnetometer (VSM), EDS (energy dispersive X-ray spectroscopy), and elemental mapping. N-Sulfonyl-N-aryl tetrazoles were synthesized in high yields from N-sulfonyl-N-aryl cyanamides and sodium azide using Ps@Tet-Cu(II)@Fe3O4 nanocatalyst. The Ps@Tet-Cu(II)@Fe3O4 complex can be recycled and reused easily multiple times using an external magnet without significant loss of catalytic activity

Pd(0) nanocatalyst stabilized on a novel agar/pectin composite and its catalytic activity in the synthesis of biphenyl compounds by Suzuki-Miyaura cross coupling reaction and reduction of o-nitroaniline

WOS: 000433204900006PubMed: 29804998The most important parameters for the fabrication of metallic nanoparticles are their synthesis method and the selection of stabilizer. These properties influence durability, shape, size, distribution, and catalytic performance of metallic nanoparticles. Therefore, a novel agar/pectin composite (APC) was designed in this study as a stabilizer, and then palladium nanocatalyst (Pd NPs@APC) was synthesized using green protocol which contains no hazardous reducing agents. The results of the thermal analysis showed that Pd NPs@APC had highly thermal durability (239 degrees C). Palladium nanoparticles were in spherical shape and homogeneously dispersed on APC surface. In addition, the particle sizes of palladium nanoparticles were determined as 34-54 nm. Catalytic activity of Pd NPs@APC was investigated in (i) Suzuki-Miyaura cross coupling reactions by using microwave irradiation to decrease high reaction time and energy as well as to provide clean synthesis and (ii) the reduction of o-nitroaniline to 1,2-benzenediamine at room temperature in water. Catalytic tests showed that Pd NPs@APC had high activity and sustainability performance against both Suzuki-Miyaura reactions and the reduction of onitroaniline

Synthesis of water soluble o-carboxymethyl chitosan-imine supported some complexes and their applications

Bu çalışmada 4 yeni suda çözünebilir O-karboksimetil kitosan Schiff bazı ve onların Cu(II), Pd(II) kompleksleri sentezlendi. Sentezlenen O-karboksimetil kitosan Schiff bazları[OCMCS-3a].2H2O, [OCMCS-4a].2H2O, [OCMCS-5a], [OCMCS-6a] ve metal komplekslerinin yapıları FTIR, 1H NMR, 13C NMR, 13C CP-MAS NMR, TG/DTG, XRD, SEM-EDAKS, ICP, UV-VIS, elementel analiz, manyetik moment ve molar iletkenlik ölçümleri ile karakterize edilmiştir. [OCMCS-3a].2H2O, [OCMCS-4a].2H2O, [OCMCS-5a] ve [OCMCS-6a] bileşiklerinin sübstitüsyon dereceleri (DS) yapılan elementel analiz sonucunda sırası ile 0.36, 0.34, 0.48 ve 0.44 olarak belirlenmiştir. Yapılan çözünürlük testi ile [OCMCS-3a].2H2O, [OCMCS-4a].2H2O, [OCMCS-5a] ve [OCMCS-6a] bileşiklerinin oda sıcaklığında saf suda tamamen çözündüğü kaydedilmiştir. Kitosan, O-karboksimetil kitosan Schiff bazları ve komplekslerinin yüzey görüntüleri SEM-EDAKS tekniği ile araştırılmıştır. Sentezlenen bileşiklerin termal davranışları TG/DTG tekniği ile kristaliniteleri ise X-ışını toz kırınım tekniği kullanılarak belirlenmiştir. Elde edilen komplekslerin metal içerikleri ICP-OES cihazı kullanılarak belirlenmiştir. Yapılan analizler sonucunda O-karboksimetil kitosan Schiff bazları ve komplekslerinin kitosana göre termal kararlılıklarında ve kristalinite değerlerinde azalma kaydedilmiştir. Yapılan yüzey incelemesi sonucunda kitosanın yüzey yapısının, elde edilen bileşiklere göre daha düz bir yapıda olduğu da kaydedilmiştir. Ayrıca sentezlenen metal komplekslerinin katalitik aktiviteleri Suzuki çapraz kenetlenme reaksiyonları ile biarillerin sentezinde test edilmiştir. Sentezlenen biarillerin yapıları GC-MS ve 1H NMR teknikleri ile aydınlatılmıştır. Deneyler sonucunda, sentezlenen Pd(II) katalizörleri varlığında, reaksiyonlar yüksek seçicilik göstermiş ve homo kenetlenme yan ürünleri spektrumlarda gözlenmemiştir. Katalizörlerin tekrar kullanılabilirlik testleri sonucunda katalizörlerin birden fazla kez kullanılabildiği belirlenmiştir.In this study, four new water soluble O-carboxymethyl chitosan Schiff bases and their Cu(II) and Pd(II) complexes were synthesized. These synthesized O-carboxymethyl Schiff bases [OCMCS-3a].2H2O, [OCMCS-4a].2H2O, [OCMCS-5a] and [OCMCS-6a] and their metal complexes were characterized by FTIR, 1H NMR, 13C NMR, 13C CP-MAS NMR, TG/DTG, XRD, SEM-EDAX, ICP, UV-VIS, elemental analysis and magnetic moment and molar conductivity measurements. Degree of substitution (DS) of [OCMCS-3a].2H2O, [OCMCS-4a].2H2O, [OCMCS-5a] and [OCMCS-6a] compounds were determined by elemental analysis as 0.36, 0.34, 0.48 and 0.44, respectively. It was specified by solubility tests that [OCMCS-3a].2H2O, [OCMCS-4a].2H2O, [OCMCS-5a] and [OCMCS-6a] compounds were completely soluble in pure water. Surface images of chitosan, O-carboxymethyl chitosan Schiff bases and their metal complexes were investigated by SEM-EDAX technique. Thermal behaviors and crystallinities of synthesized compounds were determined by TG/DTG and X-ray powder diffraction techniques, respectively. Metal contents of obtained complexes were determined by ICP-OES instrument. As a result of the analyses, it was noted that thermal stabilities and crystallinities of O-carboxymethyl chitosan Schiff bases and their complexes were decreased as compared to chitosan. In consequence of surface screening, it was also noted that surface structure of chitosan was smoother than that of obtained compounds. Furthermore, catalytic activities of synthesized metal complexes were tested by Suzuki cross-coupling reactions in the synthesis of biaryl. Structures of synthesized biaryl were identified by GC-MS and 1H NMR techniques. As a result of the analyses, high selectivity were obtained in the reactions and by-products of homo coupling were not seen in the spectra in the presence of Pd(II) catalysts. It was determined that the catalysts could be used for several times in consequence of reusability tests

A new chitosan Schiff base supported Pd(II) complex for microwave-assisted synthesis of biaryls compounds

WOS: 000401593400061In this study, a new heterogeneous palladium (II) catalyst that contains O-carboxymethyl chitosan Schiff base has been designed for Suzuki coupling reactions. The chemical structures of the synthesized catalyst were characterized with the FTIR, TG/DTG, ICP-OES, SEM/EDAX, H-1 NMR, C-13 NMR, GC/MS, XRD, and magnetic moment techniques. The reusability and catalytic behavior of heterogeneous catalyst was tested towards Suzuki reactions. As a result of the tests, excellent selectivity was obtained, and by-products of homo coupling were not seen in the spectra. The biaryls products were identified on a GC/MS. In addition, it was determined in the reusability tests that the catalysts could be used several times (seven runs). More importantly, with very low catalyst loading (6 x 10(-3) mol %) in very short reaction time (5 min), chitosan Schiff base supported Pd(II) complex gave high TON and TOF values. These findings showed that Schiff base supported Pd(II) catalyst is suitable for Suzuki cross coupling reactions. (C) 2017 Elsevier B.V. All rights reserved

Production and application of highly efficient and reusable palladium nanocatalyst decorated on the magnetically retrievable chitosan/activated carbon composite microcapsules

WOS: 000465575500006This study reports (i) the production of magnetically retrievable microcapsules as immobilizing agents, which are composed of chitosan/activated carbon composite (CS-AC/Fe3O4), (ii) the green synthesis of highly stable palladium nanoparticles on CS-AC/Fe3O4 without using any toxic reducing agents (Pd NPs@CS-AC/Fe3O4), (iii) the investigation of catalytic behavior of Pd NPs@CS-AC/Fe3O4 in Suzuki-Miyaura reactions of different aryl iodides, bromides, and chlorides, and (iv) the examination of recoverability and reusability of Pd NPs@CS-AC/Fe3O4. The characterization of Pd NPs@CS-AC/Fe3O4 was performed by FT-IR, TG/DTG, XRD, SEM, and EDS analyses. It was found that the average sizes of palladium nanoparticles were changed in the range of 31-48nm. The catalytic tests revealed that Pd NPs@CS-AC/Fe3O4 was a very effective catalyst against synthesis of various biaryl compounds via Suzuki-Miyaura reactions, by giving high reaction yields under mild reaction conditions. Furthermore, it was found that Pd NPs@CS-AC/Fe3O4 was a highly retrievable and practical nanocatalyst due to its reusable nature. Pd NPs@CS-AC/Fe3O4 gave 95% of yield after ten successive cycles. These results show that Pd NPs@CS-AC/Fe3O4 is a superb catalyst and it can be applied in different catalytic systems or industrial applications due to the fact that it offers notable advantages such as high catalytic performance, reusability, stability, excellent functional group tolerance, wide substrate scope, and simple separation. [GRAPHICS]

Solvent-free, microwave-assisted highly efficient, rapid and simple synthesis of biphenyl compounds by using silica based Pd(II) catalyst

WOS: 000424268800008To maintain catalytic performance of any catalyst for a long time, the selection of support material is a very important parameter for heterogeneous catalytic systems, and this performance makes the catalyst valuable. In view of its low cost and availability, silica can be considered as a good support material for transition metal ions in the cross coupling reactions. Therefore, this study describes i) silica-gel based palladium catalyst with a long-term catalytic performance, ii) rapid, simple, economic, and green procedure which was developed for Suzuki reactions. The catalyst showed superior reusability (ten runs) and catalytic efficiency against coupling reactions under mild conditions (50 degrees C, 5min and air atmosphere). Moreover, the catalyst gave partially good reaction yields with aril chlorides which have poor activity in coupling reactions. In addition, an excellent turnover number (TON: 66000) and frequency (TOF: 825000) were obtained using very small catalyst loading (1.5 x 10(-3) mol %). This paper concludes that silica-gel based Pd(II) catalyst and the protocol of synthesis of biaryls were suitable for coupling reactions

Practical, economical, and eco-friendly starch -supported palladium catalyst for Suzuki coupling reactions

WOS: 000398425800048PubMed: 28254611In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent -free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5 min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds.(C) 2017 Elsevier Inc. All rights reserved

Pd NPs@Fe3O4/chitosan/pumice hybrid beads: A highly active, magnetically retrievable, and reusable nanocatalyst for cyanation of aryl halides

In this study, Fe3O4/chitosan/pumice hybrid beads were developed as a new stabilizer agent, and palladium nanoparticles (Pd NPs) were successfully decorated on the designed stabilizer without adding any toxic reducing resource. Then, the potential use of Pd NPs@Fe3O4/chitosan/pumice hybrid beads as a heterogeneous catalyst against different aryl halide cyanations was investigated with K4[Fe(CN)6]. In these reactions, Pd NPs@ Fe3O4/chitosan /pumice hybrid beads showed high catalytic activity by converting aryl halides to the desired benzonitriles with high product yields (80 %–98 %). Due to the magnetically separable nature of Pd NPs@Fe3O4/chitosan/pumice hybrid beads, they were reused several times, and 86 % yield was obtained even after six successive runs. This paper reveals that Pd NPs@Fe3O4/chitosan/pumice hybrid beads have a high potential to synthesis a broad range of nitriles due to their excellent catalytic and retrievable capability