Effects of processing parameters in P/M steel forging on part properties: A review part I powder preparation,compaction, and sintering

In the last decade, powder metallurgy (P/M) technology has made marked advances in competitive manufacturing. P/M offers design opportunities that are not possible with other methods, as well as significant cost savings. In the automotive industry, P/M forgings are being developed for applications requiring good high- cycle fatigue properties. The processing parameters, material characteristics, individual stages of compaction and parts production, deformation and densification mechanics and tooling, and preform design influence the properties of the P/M part and related economics. Therefore, a review of the various parameters involved in the different stages of P/M steel forging in net-shape manufacturing and their implications on resulting properties of the P/M parts is presented in a three part review. Key parameters in steel powder preparation, compaction, and sintering of P/M forging and their effect on part properties are described in Part I. Part II discusses issues of forging the sintered compact, and Part III reviews currently available analysis methods for studying the powder forging process.     

The evaluation of lyophilized polymer matrices for administering recombinant human bone morphogenetic protein-2

Novel unitary devices, prepared by lyophilization of viscous solutions of sodium carboxymethylcellulose (CMC) and methylcellulose (MC), were evaluated as sustained-release delivery systems for recombinant human bone morphogenetic protein-2 (rhBMP-2). In vitro characterization of the unitary devices, which contained rhBMP-2-loaded poly (d,l lactide-co-glycolide) (PLGA) bioerodible particles (BEPs), was conducted over a 2-month period. Determinations included buffer uptake, mass and molecular weight loss and rhBMP-2 release from the unitary devices. CMC devices imbibed approximately 16 times their weight of buffer, while with MC, equilibrium uptake was approximately 6 times the dry weight of the devices. Overall mass loss percentages were approximately 55 and 35%, respectively, for CMC and MC devices. rhBMP-2 release from the devices was essentially a triphasic process: an initial phase during which "free" protein (rhBMP-2 present on the surface and within the pores of the PLGA BEPs) was released, a lag period during which no release was discerned, and then release of "bound" rhBMP-2 (protein adsorbed to the BEPs). The release of bound protein correlated with the mass loss of the polymer which began after 3 weeks. Release from the unitary devices was lower than that from the BEPs alone, due to a retardation effect of the gelled CMC/MC polymers. In rabbits in which full-thickness cranial bone defects were created, the implants were well tolerated and induced significant new bone growth during an 8-week evaluation period. The CMC devices appear to have induced bone earlier (at 2 weeks), but this did not affect eventual 8-week results. CMC devices without rhBMP-2 appeared to provide some bone conduction, in contrast to the blank MC devices.     

Design optimization of deep groove ball bearings using crowding distance particle swarm optimization

This paper presents a crowding distance particle swarm optimization technique to optimize the design parameters of deep groove ball bearings. The design optimization problem is multi-objective in nature. The considered objectives are maximizing dynamic and static load bearing capacities and minimizing elasto-hydrodynamic film thickness. The technique is applied to bearings used in transmission system of a tractor for the purpose of farming. Pareto optimal solutions are obtained using the proposed technique. The results obtained from the technique are found to be superior compared with NSGA-II and catalogue values.     

Modulatory Effects of Biosynthesized Gold Nanoparticles Conjugated with Curcumin and Paclitaxel on Tumorigenesis and Metastatic Pathways—In Vitro and In Vivo Studies

Background: Breast cancer is the most common cancer in women globally, and diagnosing it early and finding potential drug candidates against multi-drug resistant metastatic breast cancers provide the possibilities of better treatment and extending life. Methods: The current study aimed to evaluate the synergistic anti-metastatic activity of Curcumin (Cur) and Paclitaxel (Pacli) individually, the combination of Curcumin–Paclitaxel (CP), and also in conjugation with gold nanoparticles (AuNP–Curcumin (Au-C), AuNP–Paclitaxel (Au-P), and AuNP–Curcumin–Paclitaxel (Au-CP)) in various in vitro and in vivo models. Results: The results from combination treatments of CP and Au-CP demonstrated excellent synergistic cytotoxic effects in triple-negative breast cancer cell lines (MDA MB 231 and 4T1) in in vitro and in vivo mouse models. Detailed mechanistic studies were performed that reveal that the anti-cancer effects were associated with the downregulation of the expression of VEGF, CYCLIN-D1, and STAT-3 genes and upregulation of the apoptotic Caspase-9 gene. The group of mice that received CP combination therapy (with and without gold nanoparticles) showed a significant reduction in the size of tumor when compared to the Pacli alone treatment and control groups. Conclusions: Together, the results suggest that the delivery of gold conjugated Au-CP formulations may help in modulating the outcomes of chemotherapy. The present study is well supported with observations from cell-based assays, molecular and histopathological analyses.     

Biogas generation from bagasse-based paper mills by anaerobic digestion

Bagasse-based paper mills in developing countries do not have sophisticated waste water treatment technology to combat water pollution released by these mills. This paper presents an overview of bagasse handling and sources of waste generation, the seriousness of pollution discharge, and treatment options available to tackle the waste water derived from bagasse-based paper mills. Extensive laboratory treatability studies indicate that anaerobic digestion for biogas generation is a viable method for handling bagasse-based paper mill wastes. The waste water was treated at an organic loading of 0.8 kg BOD m^?3 day^?1 and 1.6 kg COD m^?3 day^?1 and a detention time of 10 days, achieving 90% reduction in BOD and COD without supplementation of any nutrients. With a yield coefficient of 0.5, the average quantity of cells produced per day was calculated to be 1.683 kg day^?1 or 0.25 kg cells produced kg^?1 BOD removed. Intermittent checking on excess alkalinity in the anerobic system is necessary for achieving maximum treatment efficiency.     

Pervasive power: a radioisotope-powered piezoelectric generator

A long-lasting radioisotope micropower generator for self-powered sensor microsystems promises to make pervasive computing systems more reliable. Its higher energy conversion efficiency enables microsystems with small amounts of radioactivity to realize sensor and basic computation operations. The goal is to achieve power sources that operate over a wide temperature range and for extended time periods with high reliability. To reach this goal, researchers have investigated technologies for miniature micropower applications and developed radioisotope power generators. We've created a power source employing radioactive thin films and piezoelectric unimorphs, using a nonthermal energy conversion cycle that enables much higher energy conversion efficiency.     

Design of forging dies for forming flashless ring gear blanks using finite element methods

In the forging industry today, advanced mathematical techniques such as finite element methods (FEM) are beginning to revolutionize the conventional trial-and-error methods for die design and forging process development. Cost reduction programs are being implemented to enable the forging industry to remain competitive in today’s market. Material reduction or weight savings in the quantity of metal required to make the forged part is proving to be a significant factor contributing to cost reduction. Production of ring gear blanks without producing flash reduces the input weight of metal needed to make the gear blank, thus providing cost savings on the forged part. The following paper discusses different approaches currently used to make flashless ring gear blanks. The paper also describes the application of the rigid-viscoplastic finite element code “ALPID,” developed by Battelle Labs, Ohio, in developing a hot forging process to produce flashless ring gear blanks. The metal flow simulations, using ALPID, provide a tool to design and develop die cavities for defect-free closed die forging processes for making flashless ring gear blanks. The forming loads from these simulations are then applied to the forging die and the stresses on the die analyzed using another FEM based stress analysis package (“IDEAS,” developed by SDRC, Ohio) to verify the die design for strength in the given application. Thus, finite element methods were applied in different aspects of forging die design.     

Effects of processing parameters in P/M steel forging on part properties: A review part II forging of sintered compact

In the last decade, powder metallurgy (P/M) technology has made marked advances in competitive manufacturing. P/M offers design opportunities that are not possible with other methods, as well as significant cost savings. The processing parameters, material characteristics, individual stages of parts production, deformation and densification mechanics and tooling, and preform design influence the properties of the P/M part and related economics. Therefore, a review of the various parameters involved in the different stages of P/M steel forging in net-shape manufacturing and their implications on resulting properties of the P/M parts is presented in a three-part review. Part I discussed the issues of powder preparation, compaction, and sintering in the stages of preparing a sintered compact. This review (Part II) identifies key parameters in forging the sintered compact that influence the properties of the powder forged part. Part III reviews currently available analysis methods for studying the powder forging process.     

STOCHASTIC MODELING OF NON-LINEAR SIEVING KINETICS

The feed to a sieve is classified as oversize particles, undersize particles, and near mesh size particles. The sizes of the near mesh size particles vary around that of the sieve opening; the passage of these particles through the sieve effects the separation. A stochastic approach is employed for analyzing and modeling the sieving kinetics of the near mesh size particles, usually constituting the bulk of the material required to be separated. The master equation of the process is formulated based on probabilistic considerations, describing the passage of the particles in the presence of sieve blinding. However, an analytical solution cannot be obtained directly and hence a rational approximation technique, the system size expansion, is utilized to solve the master equation. This results in a system of non-linear, coupled, ordinary differential equations for the various statistical quantities characterizing the number of particles retained on the sieve and the number of blinded apertures. These equations are then solved numerically. From these general equations, specific cases as the first order kinetics law, applicable to the terminal stages of sieving, are easily obtained. In the absence of oversize particles, the process is described by a master equation which is solved directly, yielding an explicit analytical solution. The numerical solutions agree at least qualitatively with the available experimental observations