Cellulose nanocrystals are promising materials for application in biomedicine, pharmaceutical and food industry. There are various methods for CNC synthesis, but acid hydrolysis is the most common one. The optimization of acid hydrolysis process is still in progress. In the present study, different CNC suspensions were prepared to find out the more efficient acid ratio for CNC production. Whatman #1 filter paper was hydrolyzed via 64 wt% sulfuric acid at acid-to-paper ratio of 10:1 mL/g, 20:1 mL/g, 30:1 mL/g, and 40:1 mL/g. The synthesized CNCs were characterized by DLS, ELS and AFM. The suspensions with acid/cellulose ratio of 20:1 mL/g & 30:1 mL/g resulted in CNCs with more negative surface charge and uniform size. They also represented chiral nematic phase and regular self-organization after layer by layer deposition. It was found that the higher acid-to-paper ratio does not necessarily produce the high quality CNCs. Since the suspension that was prepared at acid/cellulose ratio of 40:1 mL/g had lower negative charge. The size and surface charge of CNCs are highly dependent to acid hydrolysis parameters and ultimately affect their behavior in nano-composites. In spite of many published papers around CNC synthesis by acid hydrolysis, there are still some details that must be addressed and investigated more to prepare the most efficient and applicable CNCs. Manuscript profile

This study aimed to investigate the effect of electrical potential on the morphology of Polyvinyl Alcohol/Sodium Alginate electrospun nanofibers, containing herbal extracts of Calendula Officinalis. For this purpose, Poly Vinyl Alcohol (PVA)/ Sodium Alginate (SAlg) nanofibers were prepared using the electrospinning method in aqueous solutions with PVA (8% w / v)/SAlg (2% w / v) blended system in a volume ratio of 80/20. Then Calendula officinalis extract (10% w / v)in a volume ratio of 10% of PVA/SAlg blended system added. Applying potentials were 5, 10, 15, and 20 kV. The electrospun fibers were characterized by scanning electron microscopy (SEM). The results show that all the produced mats had high-porosity and high-surface to volume ratio of electrospun fibers. In all applied potentials, the diameter of the nanofibers containing Calendula was more than the Calendula-free Nanofibers. On the other hand, the diameters of the Nanofibers in each sample decreased with enhancing the potential. Without significant changes in mat morphology, PVA/SAlg electrospun nanofibers diameter including the Calendula could be controlled with electrical potential in electrospinning. The results could be used in antibacterial meshes, wound dressings, drug delivery, and tissue engineering applications. Manuscript profile

The primary purpose of this study is to produce a composite scaffold using polycaprolactone (PCL) and heparinized nano-fluorohydroxyapatite for cancellous bone tissue engineering. The research investigated the impact of heparinized nano-fluorohydroxyapatite particles on various properties of the scaffold, including water absorption, biodegradability, and alkaline phosphatase activity. The scaffold was produced using the phase separation (solid-liquid) method in combination with freeze-drying, and two different concentrations of heparinized nano-fluorohydroxyapatite powder were utilized. Biodegradability was assessed by submerging the scaffolds in phosphate-buffered saline for 6 weeks, showing that increased nano-fluorohydroxyapatite content enhanced biodegradability. PCL/10%w(H-nFHA50) exhibited the highest biodegradability rate. Water absorption analysis revealed that PCL scaffolds had lower water absorption compared to composite samples with heparinized nano-fluorohydroxyapatite, with PCL/10%(H-nFHA50) demonstrating the highest water absorption. Alkaline phosphatase activity was assessed on day 14 of cell culture, showing higher activity in heparinized samples compared to heparin-free samples in the presence of nano-fluorohydroxyapatite. The presence of heparin and nano-fluorohydroxyapatite in the scaffold structure likely contributed to this difference. No significant difference was observed between heparinized scaffolds with different nano-fluorohydroxyapatite concentrations. The results emphasize that the constructed scaffolds possess the potential for utilization in cancellous bone tissue engineering. Manuscript profile

In recent years, investigations on accelerating of corrosion of Fe-Mn based alloys as biodegradableones in orthopedic applications are aggrandized. Alloy composition is one of the effective factors inthis case. This study is focused on the effect of the third element on the corrosion behavior ofFe35Mn alloy. For this purpose, four alloys including Fe35Mn, Fe35Mn2Ti, Fe35Mn2Ta, andFe35Mn2Zr were produced by mechanical alloying. Then cylindrical samples of each alloy werefabricated by spark plasma sintering method (SPS) with pressing in 50MPa and sintering at 1000°Cfor 20 minutes simultaneously. All the specimens were evaluated by x-ray diffraction (XRD), lightmicroscope, and potentiodynamic polarization test to compare the effect of the third element as Ta,Ti, and Zr. Results revealed that adding the third element increases the corrosion rate. It is foundthat the most effective element was Ta. Also, the weight changes of specimens after immersion inSBF at different times for predicting their probable behavior in the human body were measured.The foundlings could be utilized in medical applications. Manuscript profile

Porous NiTi alloys has a series of unique properties such as shape memory effect, superelastic behavior and energy absorbability that make them usable in a wide range of medical and industrial appliances. But the more probability of Ni release from a porous NiTi compare to the nonporous one has restricted it’s uses in implants. In the present research for resolving the problem, performing a calcium-phosphate layer on an Iranian porous alloy was considered. For this purpose all of the samples were immersed in SBF for 3 and 5 days. Some of them passed the dipping in SBF stage after 30% HNO3 and 1.2 M NaOH solution treatments. All the samples were characterized using SEM equipped with EDS and light microscopy. The results show that the chemical treated samples had better and more uniform calcium-phosphate layer forming ability than the untreated ones. The obtained results could be used in orthopedic applications. Manuscript profile

آلیاژهای بر پایه روی (Zn) با کنترل فرآیند تولید قابلیت ظهور طیف گسترده ای از خواص مورد نیاز برای کاربرد در کاشتنی‌های کوتاه مدت درون تنی را دارند. برای این منظور در پژوهش حاضر پودر آلیاژی با ترکیب Wt Mn%4-Zn از طریق آلیاژسازی مکانیکی در سه زمان 10، 20 و 30 ساعت تهیه و قطعات آلیاژی از طریق فرآیند تف جوشی جرقه پلاسما (SPS) ساخته شدند. عملیات حرارتی قطعات تولیدی در سه دمای150، 200و250 درجه سانتی‌گراد انجام گردید. نمونه‌ها با استفاده از آزمون‌های پراش اشعه ایکس (XRD) ، خوردگی پلاریزاسیون دینامیکی و ارزیابی زنده مانی سلولی MTT مشخصه یابی شدند. همچنین مورفولوژی سطح نمونه ها با استفاده از میکروسکوپ الکترونی روبشی (SEM) مورد بررسی قرار گرفت. نتایج نشان داد افزایش زمان آسیاب به 30 ساعت ترکیبی همگن تر ایجاد نموده، همینطور نمونه عملیات حرارتی شده در دمای °C250 دارای بالاترین میزان مقاومت به خوردگی است. زنده مانی سلولی نمونه عملیات حرارتی شده در این دما نسبت به نمونه‌های دیگر زنده مانی بیشتری نشان داد. انتظار می رود نتایج این مطالعه در کاربردهای کوتاه مدت درون تنی مورد استفاده قرار گیرد. Manuscript profile

اصلاح سطح کاشتنی با ایجاد بافت سطحی لیزری بهترین روش شناخته شده برای افزایش چسبندگی است. بهترین الگوی بافت سطحی لیزری هنوز ناشناخته است. به منظور بررسی ویژگیهای دیگری از الگوی جدید پیشنهادی نویسندگان، در این پژوهش ابتدا بافتهای جدید خطوط متقاطع با زاویه های 0، 15، 30، 45، 60، 75 و 90 درجه روی سطح آلیاژ Ti6Al4V با استفاده از لیزر پالسی Nd:YAG ایجاد گردید. سپس زاویه تماس قطرات آب به دو روش 1- ثبت و آنالیز تصویر قطره و 2– بکارگیری معادلات اکسترند و مون اندازه گیری شد. قطره‌های آب در دو حجم μlit 1 و μlit 25 انتخاب شدند. با استفاده از میکروسکوپ متالورژی، SEM ، بکارگیری معادلات ونزل و کسی و رسم نمودارهای مربوطه، تاثیر زاویه بین خطوط، ارتفاع، جدایی و پهنای ستون‌های بافت سطحی بر زاویه تماس قطره بررسی شد. مدل کلاسیکی ترشوندگی بافت ها تعیین شد. نتایج نشان داد برای قطره با حجم μlit 1 زاویه تماس در هر دو روش تقریبا ثابت و مستقل از زاویه خطوط متقاطع است که سازگاری خوبی با نتایج تحقیقات قبلی دارد. برای قطره با حجم μlit 25 زاویه تماس در هر دو روش متغیر و وابسته به زاویه خطوط متقاطع می‌باشد. مدل کلاسیک ترشوندگی بافت ها در هر دو حجم قطره منطبق بر مدل ونزل می‌باشد. Manuscript profile