Chitosan extracted from the Persian Gulf chiton shells: Induction of apoptosis in liver cancer cell line

Here for the first time, we investigated the cytotoxic effects of the chitosan extracted from the Persian Gulf Chiton shell (Acanthopleura vaillantii) on liver cancer cell line (HepG_2). Chitosan extraction was implemented following this method: chitin was produced by demineralization and deproteinization procedure, and the extracted chitin was converted into soluble chitosan using deacetylation method. The cytotoxic effects of extracted chitosan were evaluated using four different tests, including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Annexin V-FITC, propidium iodide (PI) staining, 4',6-diamidino-2-phenylindole (DAPI) staining, and Caspase activity analysis. The IC_50 inhibitory concentrations of chitosan were obtained at 250 µg/mL after 24 h. Chitosan clearly inhibited the growth of hepatocarcinoma cells in vitro in a dose-dependent manner. For detecting the induced cell apoptosis, HepG_2 cells were treated with 125, 250 and 500 µg/ml of chitosan for 24 h. According to the result of Annex in V/PI kit, in 125, 250, and 500 µg/ml of chitosan, 28.2, 49.1, and 83.3% of HepG_2 cells undergone late apoptosis, respectively. The morphology of treated cells by DAPI staining showed non uniform plasma membrane and DNA fragmentation compared to untreated cells with perfect nucleus. The analysis of cell cycle using flow cytometry demonstrated that the rate of sub-G1 peak was increased to 52.7%. Both caspase-3 and -9 activities increased by the extracted chitosan, but it was only significant for caspase-3. The results of the present study suggested that the extracted chitosan has efficient cytotoxicity on HepG_2 cells. Therefore, the extracted chitosan from the shell of the Chiton may be considered as a futuristic natural product regarding the treatment of liver cancer

Electron beam structuring of Ti6Al4V: New insights on the metal surface properties influencing the bacterial adhesion

Soft tissue adhesion and infection prevention are currently challenging for dental transmucosal or percutaneous orthopedic implants. It has previously been shown that aligned micro-grooves obtained by Electron Beam (EB) can drive fibroblast alignment for improved soft tissue adhesion. In this work, evidence is presented that the same technique can also be effective for a reduction of the infection risk. Grooves 10-30 \u3bcm wide and around 0.2 \u3bcm deep were obtained on Ti6Al4V by EB. EB treatment changes the crystalline structure and microstructure in a surface layer that is thicker than the groove depth. Unexpectedly, a significant bacterial reduction was observed. The surfaces were characterized by field emission scanning electron microscopy, X-ray diffraction, confocal microscopy, contact profilometry, wettability and bacterial adhesion tests. The influence of surface topography, microstructure and crystallography on bacterial adhesion was systematically investigated: it was evidenced that the bacterial reduction after EB surface treatment is not correlated with the grooves, but with the microstructure induced by the EB treatment, with a significant bacterial reduction when the surface microstructure has a high density of grain boundaries. This correlation between microstructure and bacterial adhesion was reported for the first time for Ti alloys

New approach for time-resolved and dynamic investigations on nanoparticles agglomeration

Nanoparticle (NP) colloidal stability plays a crucial role in biomedical application not only for human and environmental safety but also for NP efficiency and functionality. NP agglomeration is considered as a possible process in monodispersed NP colloidal solutions, which drastically affects colloidal stability. This process is triggered by changes in the physicochemical properties of the surrounding media, such as ionic strength (IS), pH value, or presence of biomolecules. Despite different available characterization methods for nanoparticles (NPs), there is a lack of information about the underlying mechanisms at the early stage of dynamic behaviors, namely changing in NP size distribution and structure while placing them from a stable colloidal solution to a new media like biological fluids. In this study, an advanced in situ approach is presented that combines small angle X-ray scattering (SAXS) and microfluidics, allowing label-free, direct, time-resolved, and dynamic observations of the early stage of NP interaction/agglomeration initiated by environmental changes. It is shown for silica NPs that the presence of protein in the media enormously accelerates the NP agglomeration process compared to respective changes in IS and pH. High IS results in a staring agglomeration process after 40 min, though, in case of protein presence in media, this time decreased enormously to 48 s. These time scales show that this method is sensitive and precise in depicting the dynamics of fast and slow NP interactions in colloidal conditions and therefore supports understanding the colloidal stability of NPs in various media concluding in safe and efficient NP designing for various applications

New sesquiterpene coumarin from the roots of Ferula latisecta

Objective: The genus of Ferula belongs to the tribe Peucedaneae, subfamily of Apioideae and family of Umbelliferae with 133 species distributed throughout the Mediterranean area and central Asia, especially in the former USSR and neighboring countries such as Iran. The popular Persian name of the most of these species is “Koma”. In this research we tried to isolate and elucidate the structure of new sesquiterpene in the root of Ferula latisecta (F. latisecta). Materials and Methods: Dried and powdered roots of F. latisecta were extracted with CH2Cl2 using a Soxhlet apparatus. The extract was concentrated in vacuo to give a red extract. The extract was subjected to column chromatography on silica gel. 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HMBC, HSQC, and NOESY spectra were the methods we used to elucidate the structure of new sesquiterpene in this plant. Results: One new sesquieterpene coumarin, namely Latisectin and IUPAC name [1-(2-Hydroxy-4- methoxy-phenyl)-3,4,8,12-tetramethyl-trideca-4,7,11-trien-1-one ] , together with one known compound , Kopetdaghin C, were isolated from the root of F. latisecta. Conclusion: In this research the structure of one new and one known sesquiterpene in the root of F. latisecta was elucidated

Progress in spherical packed-bed reactors:Opportunities for refineries and chemical industries

\u3cp\u3eGiving the ever-increasing energy and raw material demand as a result of global economy growth, revisiting the traditional reactor configuration designs (which are considered to be the heart of chemical industries) can significantly reduce the capital and operational costs while addressing the larger market demand for chemicals. The spherical-reactor geometry is an attractive alternative design to traditional tubular reactors due to its lower pressure drop (which is due to feed distribution over a larger outer surface area in spherical reactors compared to the cross sectional area in conventional tubular reactors) and recompression costs as well as construction material investment (reduced wall thickness to half). This review summarizes numerical modeling and experimental research on spherical reactors from 1958 to date. Several configurations of spherical reactors have been described and categorized. A review has been performed on modeling results of numerous arrangements and combinations of tubular and spherical reactors for industrial-scale reforming processes. The superiority of spherical packed bed reactors is further discussed and additional recommendations are provided to be considered in future research. As a general conclusion, spherical reactors could be considered as a potential candidate for pilot and industrial scale reactors due to their cost-effective designs and flexibilityof operation conditions.\u3c/p\u3

Comparative thermal fatigue behavior of AlSi7Mg alloy produced by L-PBF and sand casting

By increasing the demand for additively manufactured Al parts for industrial applications, the knowledge about their thermal and mechanical behavior in service environments becomes highly required. Since Al alloys are widely used for the production of lightweight structures in transportation industry including several engine components, their thermo-mechanical behavior deserves special attention, considering the thermal and mechanical load fluctuations experienced in parts like cylinder heads, pistons, brake disks and calipers. In the present study, a comparative research has been carried out on the thermal fatigue (ThF) behavior of an AlSi7Mg (A357) alloy processed either by sand casting or laser powder bed fusion (L-PBF). Both alloy conditions were cycled within three temperature intervals with a lower temperature of 100 °C and upper limits of 200, 240 and 280 °C, in presence of a constant uniaxial tensile load. Three tensile loads of 110, 120 and 150 MPa were applied for each temperature range in order to explore the effect of both thermal cycling and concurrent tensile load on thermal fatigue resistance. Both alloys showed a similar ThF lifetime when exposed to temperature cycles from 100 to 200 °C under all the three tensile loads investigated, while the L-PBF A357 alloy tested to the highest temperature limits of 240 °C and 280 °C comparatively revealed an improved ThF resistance than the cast counterpart. Microstructural analyses on the cross-sections of both samples revealed that a large amount of strain was accumulated close to the fracture regions and several micropores and microcracks were developed in these areas. Microcracks preferentially nucleated at eutectic Si and Fe-bearing coarse intermetallics in the ThF tested cast alloy, while micropores nucleated from the fragmented silicon network in L-PBF samples on exposure to thermal cycling