Search

This research aims to examine HAMC’s tribology’s performance-[Hybrid Aluminium metal matrix composites] reinforced with Silicon carbide, Nickel & Graphite at different temperature conditions for thermal applications. This is highly significant for applications with high-temperature. The HAMCs were developed by stir casting method by reinforcing particles like SiC (5% & 10%) and Ni.-Gr. (2% fixed) into LM26 aluminium alloy. The wear rate and friction coefficient of the material is analyzed through pin-on-disc apparatus. The parameter impact on applied load, wt%, sliding distance, and the temperature is analyzed using an L9 orthogonal array. COF and wear loss of the proposed HAMC is determined using the ANOVA method. The Tribological property of HAMC is mainly influenced by applied load and temperature. The varying hybrid % controls the COF and wear loss. The SEM analysis is used to assist the performance of the worn surface.

Biopolymer electrolytes based on iota-carrageenan (I-carrageenan) with sodium trifluoromethanesulfonate (NaTf) were prepared by way of the conventional solution-casting technique. The biopolymer I-carrageenan was fixed as 1 g, and the concentration of NaTf was varied from 0.1 to 0.5 wt% in steps of 0.1 wt%. Distilled water was used as a solvent. Alternating current (AC) impedance measurements were carried out in the frequency window of 42 Hz–1 MHz. The same measurements were also carried out at different temperatures for all the prepared biopolymer samples. A maximum ionic conductivity of 2.6771 × 10−5 S/cm was obtained for the 0.3 wt% NaTf-added I-carrageenan system at room temperature. The temperature-dependent conductivity plot of the polymer electrolyte seemed to obey the Arrhenius relation. A low activation energy of 0.021 eV was observed for the sample with the highest ionic conductivity. From AC impedance data, dielectric parameters were obtained. The magnitude of the dielectric constant was found to increase with the increase in temperature. A low relaxation time was observed for the sample that possesses the maximum ionic conductivity.

The emphasis of this exploration was to examine the workability and work hardening performance of Mg (Magnesium) specimen and Mg-B4C composites created via the powder metallurgy technique. The pure Mg and Mg-B4C composites are made with distinct weight percentages (Mg-5% B4C, Mg-10% B4C, and Mg-15% B4C) at the unit aspect ratio. The powders and composites characterization are executed by SEM (Scanning Electron Microscope), EDS (Energy Dispersive Spectrum) with an elemental map, and XRD (X-ray Diffraction) examination. It displays that, the B4C particles were dispersed consistently with the Mg matrix. The workability and work hardening examination was conducted in triaxial stress conditions using the cold deformation process. The consequence of workability stress exponent factor (βσ), distinct stress proportion factors (σm/σeff and σθ/σeff), instantaneous work hardening exponent (ni), work hardening exponent (n), coefficient of strength (k) and instantaneous coefficient of strength (ki) are recognized. The outcome displays that Mg-15% B4C specimen has greater workability and work hardening parameter, initial relative density, and triaxial stresses compared with the Mg specimen and Mg-(5–10%) B4C composites.

So far many attempts have been made to synthesize phase-pure Ti3AlC2 MAX-phase. But still the challenge posed by the presence of TiC and Ti-Al based intermetallic transient impurity phases in the final product is a persisting problem. Spark plasma sintering (SPS) technique has been the most successful method to decrease the impurity content of the final product. Even so, synthesis of phase-pure Ti3AlC2 MAX-phase, without any TiC and Ti-Al based intermetallic impurities, has not been achieved and reported in literature with substantial evidences. Further, high purity Ti3AlC2 MAX-phase synthesized using SPS technique has shown lack of phase and microstructural stability above 1350°C temperature. In this work, we have reported an optimized method for producing phase-pure Ti3AlC2 MAX-phase (having more than 99 % purity) using commercial grade Ti, Al and C elemental powders through SPS technique. The final product also showed very good high temperature stability up to 1500°C under flowing Argon inert atmosphere.

The development of photocatalytic systems composed of earth-abundant metal-based catalysts for efficient production of clean fuel, H2 as well as value-added chemicals is of significant importance towards sustainable generation of energy resources. Consequently, herein we report rational construction of Z-scheme CoTiO3/xZn0.5Cd0.5S (x = 5 (S1), 10 (S2), 15 (S3) and 20 wt% (S4)) heterostructures featuring suitable band structure for efficient photocatalytic reduction of protons of water to H2 combined with selective oxidation of furfuryl alcohol (biomass derivative) to a value-added product, furfuraldehyde. Electron microscopy analysis of heterostructure S2 revealed that Zn0.5Cd0.5S nanoparticles are decorated over the surface of CoTiO3 microrods. The photocatalytic studies showed higher catalytic performance by S2, for selective oxidation of furfuryl alcohol to furfuraldehyde with 95% yield coupled with a H2 generation rate of 1929 μmol g−1h−1 which is about 4-fold higher than that of pristine Zn0.5Cd0.5S. The enhanced catalytic performance of heterostructure S2 has been ascribed to synergistic interaction aided by the Z-scheme heterojunction formation between CoTiO3 and Zn0.5Cd0.5S. Overall, this work demonstrates the application of noble metal-free photocatalyst for simultaneous production of H2 and value-added chemical under mild and environment-friendly conditions.

In the present work the drying characteristics and proximate analysis of turkey berry (Solanum torvum) were analyzed under open sun drying and greenhouse drying with two different glazing materials (UV Polyethylene sheet and Drip lock sheet) under passive and active modes. The drying rate under different modes of drying are 18.73g/h in drip lock greenhouse active mode,12.50 g/h in UV polyethylene sheet greenhouse active mode,15.22 g/hin drip lock sheet greenhouse passive mode, 11.84 g/h in UV polyethylene sheet greenhouse passive mode and 10.65 g/h in open sun drying. Twelve mathematical models were chosen to determine the drying characteristics of Turkey berry. From the statistical analysis it is found that Modified Henderson and Pabis model is the best drying model describing thin layer drying characteristics of turkey berry in both open sun drying and green house drying. The goodness of the fit achieved is based on the values of coefficient of determination(R2), sum square error(SSE), root mean square error(RMSE) and reduced chi square (χ2).From the proximate analysis of dried turkey berry it is found that more amount of carbohydrate is retained in UV polyethylene greenhouse dryer under passive mode. In drip lock greenhouse dryer under passive mode the retention of vitamins such as protein, vitamin C and ash content showed a positive sign. In drip lock greenhouse dryer under active mode the retention of calcium, iron and dietary fibre is found to be high. Finally it is observed that more amounts of nutrients are retained in greenhouse drying than in open sun drying.

This study proposed the methodology to produce silicon carbide particulate MMCs based on aluminum to create typical low-cost MMCs and achieve a homogeneous scattering of ceramic material. The trial was done with a different weight fraction of Silicon Carbide (2%, 3%) and Tungsten Carbide (2%, 3%) with all other parameters being maintained. A growing hardness was noticed with the rise in SiC & WC weight 2 to 3%. The advantages of this technique include improved mechanical characteristics, minimal residual stress and deformation, and fewer flaws. Although casting technique poses numerous technical obstacles, this problem can nevertheless be addressed. Aluminum materials with high strength to weight and low density have been proven to be the best option. As lightweight materials are developed, weight reduction has been offered several alternatives through conducting different tests to analyze different features such as mechanical and metallurgical characteristics.

This paper proposed the methodology of dissimilar welding of Inconel materials in Friction stir welding process. For the great mechanical and thermal properties the Inconel alloys are preferered. Inconel alloys are used in aerospace and petro chemical industries for its good thermal properties. The requirement for prudent and productive utilization of materials regularly requires the joining of different metals. This research analyse the, welding between Inconel 600 and Inconel 718, was endeavored to utilize rotating grating welding. The qulity of the weld is achived by the weld deposite without unwanted Laves or delta stages. Grain coarsening in weld affected zone was investigated by the weld thermal cycle. At room temperature tractable tests, the joints were found to fall flat in the HAZ of Inconel 718, showing great extreme elasticity (759 MPa) without a critical deficiency of malleable flexibility (21%). A filtering electron infinitesimal assessment of the break surfaces uncovered fine dimpled crack highlights, recommending a break in a pliable mode.

AIM This study aimed at evaluating the influence of cortical layer and surgical techniques on the primary stability of implants in low-density bone. MATERIALS AND METHODS Two solid rigid polyurethane blocks with a density equivalent to 0.32 g/cm3 simulating cancellous bone were used. A short fiber-filled epoxy resin sheet of 2 mm was layered to one block to simulate cortico cancellous bone. A total of 40 implants were used in this study (n = 40). Twenty implants each (n = 20) were inserted in cancellous (Group 1) and cortico-cancellous bone (Group 2), of which 10 implants each (n = 10) were placed using undersized preparation technique with surgical drills-A and osteotomes-B, in both the groups. Insertion torque (IT) and implant stability quotient (ISQ) for each implant placed were assessed to determine the primary stability of each implant using a digital torque meter and resonance frequency analyzer, respectively. The values were statistically analyzed using an independent t-test (p < 0.05). Pearson's correlation analysis was performed to correlate between IT and ISQ. RESULTS Technique B resulted in significantly higher IT and ISQ values in Group 1 (27.69 ± 1.2 N cm; 52.5 ± 1.05 ISQ) and Group 2 (38.8 ± 0.87 N cm; 70.1 ± 1.04 ISQ) compared to those with technique A (22.40 ± 1.62 N cm; 41.75 ± 1.20 ISQ and 33.24 ± 0.67 N cm; 63.72 ± 1.33 ISQ), respectively. Group 2 exhibited significantly higher IT and ISQ values as compared to Group 1 irrespective of the surgical technique employed (p < 0.05). CONCLUSION The presence of the cortical layer significantly influenced the primary stability and preparing low-density bone with an undersized preparation technique using osteotomes that significantly increased the IT and ISQ. CLINICAL SIGNIFICANCE Undersizing the preparation site considerably will help achieve a significant increase in primary stability in the poor quality bone as in the posterior maxilla, thereby contributing to the success of the implant.

Morphological modification in materials aids multi-channel electron access sites for easier electrolyte ion access for many electrochemical devices including energy storage devices. Controlled synthesis of such multichannel morphologies of metal oxides offers significant challenges. Herein, we report a template-assisted electrodeposition technique for the synthesis of Cu nanowires, which are transformed into either CuO nanotubes by controlled annealing or CuO hierarchical nanospikes using a simple hydroxyl ion impregnation technique and subsequent annealing. These materials are tested as electrodes in charge storage systems in 6 M KOH electrolyte in a three-electrode system; both electrodes have shown battery-type charge storage behaviour. Despite the chemical similarity between the two materials, the CuO nanospikes electrodes showed improved charge transport between electrode-electrolyte interface compared to the CuO nanotubes. With the cost-effectiveness, easy availability, and multi-channel morphology of CuO nanospikes along with the promising performance of the electrode in a three-electrode system, the present research offers future potential in developing low cost and high performing energy storage devices.

We employed the computational fluid dynamics (CFD) simulation to capture the flow behavior in spinnerets based on various flow angles (90°, 75°, 60°, and 30°), different power-law fluids (0.5 ≤ n ≤ 1), and two different flow rates (0.2 mL/min and 1.4 mL/min). The simulation results moderately agreed with the semi-analytical solution obtained from the literature. The sensitivity analysis was performed, showing that spinneret's flow angles and power-law indices are additional critical variables that facilitate the alignment of the polymeric chain in the dope solution due to the enhanced shear rate. The maximum viscosity reduction is observed in this study when a more shear-sensitive dope fluid extrudes through the spinneret at a given flow rate. The low shear rate gradient prevalence elevates the viscosity in the annular spinneret region, strongly dependent on the flow and shear-sensitive fluid (n

Over exploitation of non-renewable energy reserves will lead to increase in price of petroleum fuels. Therefore there is a need for suitable and sustainable substitutes (renewable resource) for conventional fuels. In this study, an efficient and environmental friendly method for production of bio-diesel from Pongamia (Karanja) oil has been developed using a solar reactor. During the experimental study, the maximum temperature attained by the pongamia oil during the transesterification process was 64.1°C. The transesterification reaction was studied by varying different parameters such as reactant flow rate (5-20 LPH), stirring speed (150-450 r·min-1), catalyst loading (0.5 wt% -2 wt%) and methanol to oil ratio (3:1 to 15:1). The maximum biodiesel yield was 83.11% at a flow rate of 5 LPH, stirring speed of 350 rpm, a methanol to oil ratio of 15:1, catalyst loading of 1wt % and reaction time of 270 min. The physical and chemical properties of biodiesel was analyzed as per American Society for Testing Materials (ASTM) standards and it had density of 938 kg·m-3, viscosity (28.7 cSt), acid value (9.45 mg KOH·(g oil)-1) and flash point (215°C). The energy efficiency of solar heating process was determined by comparing the net energy ratio of direct heating process and solar heating process. For solar heating the net energy ratio (NER) was found to be 31.85 against 5.73 for direct heating. Similarly, net energy efficiency index was calculated for 10 kg production scale and was found to be increasing when scaled up which means that the solar heating process is more effective even in scaled up production.

The demand for energy storage is exponentially increasing with growth of the human population, which is highly energy intensive. Batteries, supercapacitors, and hybrid capacitors are key energy sto...

The recent trends in material science are focused toward composite materials. It has been used in a lot of real-life applications. In composite material, recently researchers concentrated on the na...

The influences of polymerization conditions, viz. the kind of catalyst, solvent medium and temperature, on thermal, molecular and structural characteristics of carbon fiber precursor polymer were investigated. The dependence of the exothermic peak temperature (Tpk) and heat release rate on the kind of polymerization process was established. An aqueous redox slurry polymer had narrow exothermic peaks (Tpk = 294–297 °C) and relatively high heat release rates (∆H/∆T = 0.96–3.3 J g−1 s−1), and polymers prepared in solid state, solution and bulk had a broader exotherms with Tpk in the range 264–318 °C and low heat release rates in the range 1.15–3.9 J g−1 s−1. Dynamic and thermomechanical analyses indicate three glass transition temperature ranges, i.e., 42–54 °C, 80–98 °C, and 140–142 °C, which are similar irrespective of catalysts. Branching tendency in aqueous redox slurry polymer was notable beyond the intrinsic viscosity of 250 cm3/g. Bulk densities of the polymers were found to be in the range 0.25–0.45 g cm−3.

The fascinating optoelectronic properties of semiconductor quantum dots (QDs) originate from the quantum confinement effect; i.e., the band gap increases as the size decreases. Another significant ...

The transportation industry has eyes set on light weighting its products. While topology optimization aided design modifications, materials like Al, Mg, and its alloys have taken centre stage in the material swap. Solid cylindrical rods provide structural support and hence, light weighting is instead done on associated parts. However, there exists an opportunity to lightweight these cylindrical rods using centralized holes without compromising on structural integrity. Tests on materials like AZ31B, Al6065, Al7075, SS304, and mild steel showed up to 11.6% increase in compressive yield strengths and up to 5% increase in ductility. The same is discussed in this work.

Hierarchically porous crystalline nanoporous aerogels of syndiotactic polystyrene (sPS) received much attention because of their unique nanoporous structures along with meso- and macroporosity. Dep...

Various contents of graphene nanoplatelets (GNPs), ranging from 0 to 0.7 wt%, with an efficient solvent method were used to reinforce flax/epoxy composites and thereby correlate GNPs network formation with the degree of reinforcement in resultant nanocomposites. The microstructural features characterised by wide X-ray diffraction (WAX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) determined a correlation between GNPs reinforcing efficiency, nanolayers network formation and the number of layers. TEM analysis clarified that with a change in GNPs content, the distribution of nanolayers transformed from a zonal distribution to efficiently bridged networks contributing to maximum improvement in tensile and flexural properties at 0.5 wt% of GNPs. This was supported by morphological observations developed by SEM confirming various reinforcing mechanisms thanks to GNPs networks leading to enhanced interfacial adhesion between fibre and matrix. Likewise, with formation of networks, crack length at the interface of fibre and matrix and crack density in nanocomposites, determined from optical microscopy images of tensile-tested samples, received a significant decrease. TEM observations also proved that plane-to-plane and edge-to-edge contact areas of GNPs had paramount influences on reinforcement efficiency in nanocomposites. Exceeding the optimum content (0.5 wt%), the load transfer capability induced by GNPs network formation was adversely affected by plane-to-plane contacts of GNPs eventually leading to substantial reductions in mechanical properties. In drop weight impact analysis, GNPs networks also enhanced crack initiation energy and consequently reduced crack propagation energy and damage area in nanocomposites.

Utilisation of high carbon alcohols in diesel engines as fuel is gaining importance among researchers because of its better fuel properties that are compatible with mineral diesel. The present study utilises two such alcohols namely octanol and decanol along with diesel and biodiesel derived from lemongrass. Two ternary blends, 50% by volume of diesel – 30% by volume of biodiesel – 20% by volume of octanol, and 50% by volume of diesel – 30% by volume of biodiesel – 20% by volume of decanol, were prepared, and different engine characteristics were analysed and compared with both neat diesel and biodiesel operation. Results indicated that peak cylinder pressure lowered with the ternary blend. Peak heat release rate was higher for octanol blend. When compared with octanol blend, 2.5% higher brake thermal efficiency was observed for decanol blend. However, still, the brake thermal efficiency was 3.5% lower than the diesel operation. The oxides of nitrogen emission for decanol blend were 4% lower than octanol blend. In general, smoke emission was lower for higher alcohol blends in comparison with the binary blend operation. Among the higher alcohol blends, octanol portrayed a 15% lower smoke opacity. Both the hydrocarbon emission and the carbon monoxide emission increased with higher alcohol blends. The study revealed that 1-decanol could be a potential fuel candidate for diesel engines operating with biomass-derived lemongrass oil biodiesel.

Epoxy syntactic foams (SF) filled with hollow glass microspheres (HGM) were prepared by simple resin casting method and characterization in this study. The effect of varying the amount of HGM on the specific mechanical and water absorption properties of SF composites were investigated. Five different composition of SF (SFT60-0.5 to SFT60-2.5) were compared with the neat epoxy matrix. The wall thickness of the microballoons differ because of its different percentile size distribution (10th, 50th and 90th), which reflects in its density variation. The results show that the specific tensile and flexural strength increases with an increasing filler (HGM) content. The density of SF filled with HGM reduces with increasing volume fraction of filler content. Scanning electron microscopy was done on the failed samples to examine the fractured surfaces. The water absorption capacity of the SF was also investigated as it relates to the HGM volume fraction variation. All the syntactic foam composition shows a better diffusion coefficient capacity than the neat epoxy resin. This makes it applicable in structural purposes and several marine application products such as Autonomous Ultimately Vehicle (AUV).

Rapid prototyping methods for the design and fabrication of polymeric labs-on-a-chip are on the rise, as they allow high degrees of precision and flexibility. For example, a microfluidic platform may require an optimization phase in which it could be necessary to continuously modify the architecture and geometry; however, this is only possible if easy, controllable fabrication methods and low-cost materials are available. In this paper, we describe the realization process of a microfluidic tool, from the computer-aided design (CAD) to the proof-of-concept application as a capture device for circulating tumor cells (CTCs). The entire platform was realized in polymethyl methacrylate (PMMA), combining femtosecond (fs) laser and micromilling fabrication technologies. The multilayer device was assembled through a facile and low-cost solvent-assisted method. A serpentine microchannel was then directly biofunctionalized by immobilizing capture probes able to distinguish cancer from non-cancer cells without labeling. The low material costs, customizable methods, and biological application of the realized platform make it a suitable model for industrial exploitation and applications at the point of care.

The present study aims to prepare and And Characterization of zein nanofibers with simvastatin-loaded in it by electrospinning method using a polymeric matrix prepared from zein solution containing simvastatin antibiotics. The physical, cellular properties and drug release kinetics of the fibers were studied. Fiber formation was investigated by implementing a scanning electron microscope (SEM). The SEM images show a uniform network bead-free fiber structure created from the 1.5% simvastatin/zeinsolution. The viscosity of the 1.5% simvastatin/zein mixture increased to 0.402 P due to the presence of drug in zein solution. Also, the presence of the indicative peaks associated with simvastatin in the Fourier transform infrared (FTIR) spectra of the samples containing the drug, verifies the existence of the drug on the polymeric base of zein/polyethylene oxide (PEO). Also, around 53.887% of the loaded drug was released in the first 12 h of the release kinetics assay and the results of the MTT assay shows reduction in the number of live cells in the test sample. In conclusion, zein nanofibers containing simvastatin drug were found to be potential biodegradable polymers that can find application in bone tissue repair.

We report the unique growth of nanofibers in silica and borosilicate glass using femtosecond laser radiation at 8 MHz repetition rate and a pulse width of 214 fs in air at atmospheric pressure. The nanofibers are grown perpendicular to the substrate surface from the molten material in laser-drilled microvias where they intertwine and bundle up above the surface. The fibers are few tens of nanometers in thickness and up to several millimeters in length. Further, it is found that at some places nanoparticles are attached to the fiber surface along its length. Nanofiber growth is explained by the process of nanojets formed in the molten liquid due to pressure gradient induced from the laser pulses and subsequently drawn into fibers by the intense plasma pressure. The attachment of nanoparticles is due to the condensation of vapor in the plasma.

Applications of biomaterials in cancer therapy has been limited to drug delivery systems and markers in radiation therapy. In this article, we introduce the concept of phase-functionalization of silicon to preferentially select cancer cell populations for survival in a catalyst and additive free approach. Silicon is phase-functionalized by the interaction of ultrafast laser pulses, resulting in the formation of rare phases of SiO2 in conjunction with differing silicon crystal lattices. The degree of phase-functionalization is programmed to dictate the degree of repulsion of cancer cells. Unstable phases of silicon oxides are synthesized during phase-functionalization and remain stable at ambient conditions. This change in phase of silicon as well as formation of oxides contributes to changes in surface chemistry as well as surface energy. These material properties elicit in precise control of migration, cytoskeleton shape, direction and population. To the best of our knowledge, phase-functionalized silicon without any changes in topology or additive layers and its applications in cancer therapy has not been reported before. This unique programmable phase-functionalized silicon has the potential to change current trends in cancer research and generate focus on biomaterials as cancer repelling or potentially cancer killing surfaces.

We report a unique study performed on the modal transition laser fluence of agglomerated nanoparticle size distributions and their averages in three-dimensional nanostructures that were formed on aluminosilicate ceramic using a megahertz femtosecond laser. At low repetition rates, bimodal particle distributions were obtained and changed to unimodal distributions with the increase in repetition rate. The distribution modals obtained depend only on the laser fluence and the presence of photoionized species were the possible reason for the formation of bimodal distributions. Laser fluence and heat accumulation could have played key roles in determining the average particle sizes. Our study would help to enhance the properties of 3-D agglomerated nanostructures.

Recent research in the field of photovoltaic and solar cell fabrication has shown the potential to significantly enhance light absorption in thin-film solar cells by using surface texturing and nanostructure coating techniques. In this paper, for the first time, we propose a new method for nano sandwich type thin-film solar cell fabrication by combining the laser amorphization (2nd solar cell generation) and laser nanofibers generation (3rd solar cell generation) techniques. In this novel technique, the crystalline silicon is irradiated by megahertz frequency femtosecond laser pulses under ambient conditions and the multi-layer of amorphorized silicon and nano fibrous layer are generated in the single-step on top of the silicon substrate. Light spectroscopy results show significant enhancement of light absorption in the generated multi layers solar cells (Silicon Oxide nanofibers / thin-film amorphorized silicon). This method is single step and no additional materials are added and both layers of the amorphorized thinfilm silicon and three-dimensional (3D) silicon oxide nanofibrous structures are grown on top of the silicon substrate after laser irradiation. Finally, we suggest how to maximize the light trapping and optical absorption of the generated nanofibers/thin-film cells by optimizing the laser pulse duration.

Surface-enhanced Raman scattering (SERS)-based cancer diagnostics is an important analytical tool in early detection of cancer. Current work in SERS focuses on plasmonic nanomaterials that suffer from coagulation, selectivity, and adverse biocompatibility when used in vitro, limiting this research to stand-alone biomolecule sensing. Here we introduce a label-free, biocompatible, ZnO-based, 3D semiconductor quantum probe as a pathway for in vitro diagnosis of cancer. By reducing size of the probes to quantum scale, we observed a unique phenomenon of exponential increase in the SERS enhancement up to ~106 at nanomolar concentration. The quantum probes are decorated on a nano-dendrite platform functionalized for cell adhesion, proliferation, and label-free application. The quantum probes demonstrate discrimination of cancerous and non-cancerous cells along with biomolecular sensing of DNA, RNA, proteins and lipids in vitro. The limit of detection is up to a single-cell-level detection., Surface enhanced Raman scattering is a bio-analytical tool and the development and optimisation of probes is an active area of investigation. Here, the authors report on the development and testing of biocompatible semiconductor zinc oxide quantum probes on a platform for cell adhesion and analysis.

We present the creation of a unique nanostructured amorphous/crystalline hybrid silicon material that exhibits surface enhanced Raman scattering (SERS) activity. This nanomaterial is an interconnected network of amorphous/crystalline nanospheroids which form a nanoweb structure; to our knowledge this material has not been previously observed nor has it been applied for use as a SERS sensing material. This material is formed using a femtosecond synthesis technique which facilitates a laser plume ion condensation formation mechanism. By fine-tuning the laser plume temperature and ion interaction mechanisms within the plume, we are able to precisely program the relative proportion of crystalline Si to amorphous Si content in the nanospheroids as well as the size distribution of individual nanospheroids and the size of Raman hotspot nanogaps. With the use of Rhodamine 6G (R6G) and Crystal Violet (CV) chemical dyes, we have been able to observe a maximum enhancement factor of 5.38 × 106 and 3.72 × 106 respectively, for the hybrid nanomaterial compared to a bulk Si wafer substrate. With the creation of a silicon-based nanomaterial capable of SERS detection of analytes, this work demonstrates a redefinition of the role of nanostructured Si from an inactive to SERS active role in nano-Raman sensing applications.

In this study we report for the first time a method for direct patterning of silicon oxide on a silicon substrate by irradiation with a femtosecond laser of Mega Hertz pulse frequency under ambient condition. Embossed lines of silicon oxide with around 3~4 µm width and less than 100 nm height were formed by controlling the parameters such as laser pulse power and frequency rate. A Scanning Electron Microscope (SEM), an optical microscopy and a Micro-Raman and Energy Dispersive X-ray (EDX) spectroscopy were used to analyze the silicon oxide layer.

The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20 nm respectively, and lengths as long as 10 μm. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PACS: 81 Materials science; 81.07.-b nanoscale materials and structures: fabrication and characterization; 81.16.-c methods of micro- and nanofabrication and processing

In this paper, we demonstrate a new method of fabricating silicon microfluidic channels filled with a porous nanofibrous structure utilizing a femtosecond laser. The nanofibrous structure can act as a membrane used for microfiltration. This method allows us to generate both the microfluidic channel and the fibrous nanostructure in a single step under ambient conditions. Due to laser irradiation, a large number of nanoparticles ablate from the channel surface, and then aggregate and grow into porous nanofibrous structures and fill the channels. Energy dispersive x-ray spectroscopy (EDS) analysis was conducted to examine the oxygen concentration in the membrane structure. Our results demonstrated that by controlling the laser parameters including pulse repetition, pulse width and scanning speed, different microfluidic channels with a variety of porosity could be obtained.

In this paper, we demonstrate a simple, fast and single-step method for fabricating self-enclosed fluidic channels via TPA. Pairs of parallel, polymerized ribs are linked by the subsequent polymerization with correctly predetermined offset between the ribs. The region, where the radicals are initiated but its concentration is below the threshold, we called it a sub-activated region. The subsequent polymerization is triggered by the overlap of the sub-activated regions of the two adjacent ribs. The dimensions of the self-enclosed channels depends on the offset between ribs, the scan speed as well as the laser parameters such as pulse energy, pulsewidth and repetition rate.

In this study, we describe the formation mechanism of web-like three-dimensional (3-D) titania nanofibrous structures during femtosecond laser ablation of titanium (Ti) targets in the presence of background air. First, we demonstrate the mechanism of ablation of Ti targets by multiple femtosecond laser pulses at ambient air in an explicit analytical form. The formulas for evaporation rates and the number of ablated particles, which is analogous to the deposition rate of the synthesized nanofibers, for the ablation by a single pulse and multiple pulses as a function of laser parameters, background gas, and material properties are predicted and compared to experimental results. Afterwards, the formation of nanofibrous structures is demonstrated by applying an existing simplified kinetic model to Ti targets and ambient conditions. The predicted theory provides nanofiber diameter dependency with the combination of laser parameters, target properties, and ambient gas characteristics. Experimental studies are then performed on titania nanofibrous structures synthesized by laser ablation of Ti targets using MHz repletion-rate femtosecond laser at ambient air. The models' predictions are then compared with the experimental results, where nanostructures with different morphologies are manufactured by altering laser parameters. Our results indicate that femtosecond laser ablation of Ti targets at air background yields crystalline titania nanostructures. The formation of crystalline titania nanostructures is preceded b thermal mechanism of nucleation and growth. The results point out that laser pulse repetition and dwell time can control the density, size, and pore size of the engineered nanofibrous structure. As the deposition rate of nanostructures is analogous to the ablation rate of the target, higher density of nanofibrous structure is seen at greater laser fluences. The predicted theory can be applied to predict ablation mechanism and nanofiber formation of different materials.

Background Natural biomaterials from bone-like minerals derived from avian eggshells have been considered as promising bone substitutes owing to their biodegradability, abundance, and lower price in comparison with synthetic biomaterials. However, cell adhesion to bulk biomaterials is poor and surface modifications are required to improve biomaterial-cell interaction. Three-dimensional (3D) nanostructures are preferred to act as growth support platforms for bone and stem cells. Although there have been several studies on generating nanoparticles from eggshells, no research has been reported on synthesizing 3D nanofibrous structures. Results In this study, we propose a novel technique to synthesize 3D calcium carbonate interwoven nanofibrous platforms from eggshells using high repetition femtosecond laser irradiation. The eggshell waste is value engineered to calcium carbonate nanofibrous layer in a single step under ambient conditions. Our striking results demonstrate that by controlling the laser pulse repetition, nanostructures with different nanofiber density can be achieved. This approach presents an important step towards synthesizing 3D interwoven nanofibrous platforms from natural biomaterials. Conclusion The synthesized 3D nanofibrous structures can promote biomaterial interfacial properties to improve cell-platform surface interaction and develop new functional biomaterials for a variety of biomedical applications.

The aim of the study was to investigate the hybrid robust optimization planning approach in intensity-modulated proton therapy (IMPT) of craniospinal irradiation (CSI).Five IMPT-based adult CSI plans in supine position were created using Raystation treatment planning system (TPS) modelled for Proteus plus proton therapy system. A hybrid planning strategy was implemented, where clinical target volume was robustly optimized (RB) for set up uncertainties and planning target volume was optimized for target coverage using minimax algorithm in the TPS. Beam angle selection, optimization, and dose calculation approach were carefully performed to ensure optimum organ at risk (OAR) sparing, even with potential setup and range errors. The complementary dose gradients in junctions were generated using spot assignment and RB technique. Dosimetric outcomes in both nominal plan and the 16 error scenarios (±3 mm setup and 3.5% range) were analyzed using standard dose volume histogram.This planning approach resulted in a homogeneous dose distribution in the target volume of CSI, including the junction regions, by explicitly reducing number of robust optimization scenarios. The proposed technique was also able to achieve excellent coverage to cribriform plate with lower lens doses and minimal dose to other OARs. Target and OAR doses in the nominal plans as well as in the worst case scenarios with setup and range errors were able to meet the predefined clinical goal.This proposed planning technique is efficient, robust against the uncertainties. It could be adopted in other proton therapy centers.