The present work investigated the effect of adding a small amount of Ti on the microstructure, physical and mechanical properties of Sn3.5Ag0.5Cu (SAC) solder. The results indicated that adding a ...small amount of Ti can slightly decrease both the melting temperature and melting range of the SAC solder alloy and that it can also effectively refine the microstructure. The eutectic colony becomes rather narrower with the addition of Ti into SAC, and the microhardness, YS, and UTS are significantly higher than to those of the other commercially available SAC solder alloys. Microstructural analysis revealed that the origin of change in mechanical properties was due to refined β-Sn grains and the formation of new Ti2Sn3 inter-metallic compounds (IMC) in the SAC-XTi solder alloys. However, when the concentration of Ti exceeded 1.0wt%, the benefits of elongation were reduced due to the small amount of coarse Ti2Sn3 in the eutectic colonies.
The influence of both TiO2 nanoparticle addition and cooling rate on the melting temperature, microstructure, and mechanical behaviour of Sn3.5Ag0.5Cu (SAC) solder alloys was studied. The composite ...solders were prepared by mechanical mixing of TiO2 nanoparticles with SAC solder. With the addition of TiO2 nanoparticles into the eutectic SAC alloy, a novel SAC composite solder was successfully prepared. The melting temperature for the SAC composite solders was only 1.56 C higher than that of the SAC solder, indicating that the novel SAC composite solder is fit for existing soldering processes. The cooling rate and TiO2 nanoparticle addition affected the solidification of the microstructure dramatically. SEM observation of the microstructure of the SAC composite solders under the rapid-cooled condition revealed fine dot-like nano-Ag3Sn IMC in the solder matrix. The ultimate tensile strength, 0.2% yield strength, and microhardness of the SAC composite solder increased with increasing TiO2 nanoparticle content by 0.25-1.0 wt% and with increasing cooling rate, which could be attributed to the dispersion strengthening mechanisms. However, the ductility of the composite solders was found to decrease because of microporosity at the Ag3Sn network grain boundary.
Pigment epithelial-derived factor (PEDF) is a potent anti-angiogenic factor whose effects are partially mediated through the induction of endothelial cell apoptosis. The pathway mediating endothelial ...cell apoptosis has not been fully established. Here we investigated the participation of peroxisome proliferator-activated receptor gamma (PPARgamma) and p53 in the apoptosis of human umbilical vein endothelial cells (HUVECs).
HUVECs pretreated with either PPARgamma antagonist or PPARgamma small interfering RNA (siRNA) suppressed PEDF-induced apoptosis as determined by TUNEL assay, annexin V-FITC/PI staining, and cleavage of procaspase-8, -9, -3. PEDF sequentially induced PPARgamma and p53 expression as observed in immunoblotting and immunofluoresence assays. PEDF also increased the transcriptional activity of PPARgamma as evident from electromobility shift assays, and p53 as determined by the phosphorylation and acetylation of p53 and the induction of Bax. The induction of p53 by PEDF was abolished by either PPARgamma antagonist or PPARgamma siRNA. PEDF-mediated HUVEC apoptosis and cleavage of procaspases were significantly attenuated by p53 siRNA.
Our observations indicate that PEDF induces HUVECs apoptosis through the sequential induction of PPARgamma and p53 overexpression. With the growing interest in anti-angiogenesis as a novel approach to cancer therapy, defining the mechanism of PEDF-mediated HUVEC apoptosis may facilitate the development of new therapeutics.
First-line treatment of metastatic pancreatic ductal adenocarcinoma (PDAC) includes nab-paclitaxel/gemcitabine. Ibrutinib, a Bruton's tyrosine kinase inhibitor, exhibits antitumor activity through ...tumor microenvironment modulation. The safety and efficacy of first-line ibrutinib plus nab-paclitaxel/gemcitabine treatment in patients with PDAC were evaluated.
RESOLVE (NCT02436668) was a phase III, randomized, double-blind, placebo-controlled study. Patients (histologically-confirmed PDAC; stage IV diagnosis ≥6 weeks of randomization; Karnofsky performance score ≥70) were randomized to once-daily oral ibrutinib (560 mg) or placebo plus nab-paclitaxel (125 mg/m2) and gemcitabine (1000 mg/m2). Primary endpoints were overall survival (OS) and investigator-assessed progression-free survival (PFS); overall response rate and safety were assessed.
In total, 424 patients were randomized (ibrutinib arm, n = 211; placebo arm, n = 213). Baseline characteristics were balanced across arms. After a median follow-up of 25 months, there was no significant difference in OS between ibrutinib plus nab-paclitaxel/gemcitabine versus placebo plus nab-paclitaxel/gemcitabine (median of 9.7 versus 10.8 months; P = 0.3225). PFS was shorter for ibrutinib plus nab-paclitaxel/gemcitabine compared with placebo plus nab-paclitaxel/gemcitabine (median 5.3 versus 6.0 months; P < 0.0001). Overall response rates were 29% and 42%, respectively (P = 0.0058). Patients in the ibrutinib arm had less time on treatment and received lower cumulative doses for all agents compared with the placebo arm. The most common grade ≥3 adverse events for ibrutinib versus placebo arms included neutropenia (24% versus 35%), peripheral sensory neuropathy (17% versus 8%), and anemia (16% versus 17%). Primary reasons for any treatment discontinuation were disease progression and adverse events.
Ibrutinib plus nab-paclitaxel/gemcitabine did not improve OS or PFS for patients with PDAC. Safety was consistent with known profiles for these agents.
•Addition of ibrutinib to nab-paclitaxel/gemcitabine did not improve efficacy outcomes for pancreatic ductal adenocarcinoma.•Primary endpoints—overall survival and investigator-assessed progression-free survival—were not met in this phase III study.•Ibrutinib treatment led to less time on treatment and lower cumulative dose for all agents compared with placebo treatment.•Reported safety was consistent with the known profiles for ibrutinib and nab-paclitaxel/gemcitabine.
This study investigated the effects of Cu addition on the microstructure and mechanical properties of Ti15SnxCu (x=0 and 2wt%) alloys. The microstructures were characterized by optical microscopy ...(OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results demonstrate that adding Cu can produced significant grain refinement and mechanical strengthening effects in Ti15SnxCu alloy. The martensitic basket-weave microstructure of Ti15Sn alloy consists of supersaturated α′/α-Ti(Sn) solid solution and nano-Ti3Sn phase. After the addition of 2wt% Cu, the microstructure of Ti15SnxCu alloy displayed a predo-dendrite structure and plate-like nano-(Ti, Sn)2Cu phase precipitated in α'-Ti(Sn,Cu) lathes. The UTS and YS of the Ti15SnxCu increased, likely due to the refinement of the cellular grain size and lamellar thickness and length, solid solution hardening, and precipitation of nano-(Ti, Sn)2Cu.
► Effect of TiO2 nanoparticles addition on the Sn0.7Cu solder alloys is discussed. ► Additions of TiO2 nanoparticles results the microstructure and mechanical property dramatically. ► Strengthening ...mechanism of SC composite solder.
Composites of SC solder reinforced with 0, 0.25, 0.5 and 1wt.% of TiO2 nanoparticles were fabricated using a mechanical technique. With increased addition of TiO2 nanoparticles, the SC nano-composite solder was found to have a slightly lower melting temperature. The addition of TiO2 nanoparticles can also effectively refine the microstructure as so β-Sn and Cu6Sn5, and increase the percentage of eutectic area. The mechanical properties (microhardness, 0.2% YS and UTS) increase with the increasing presence of reinforcement, far exceeding the strength of the eutectic SC solder. The yield strength improvement was attributed to (i) the Hall–Petch effect due to β-Sn grain size refinement. (ii) Orowan strengthening, (iii) generation of geometrically necessary dislocations to accommodate CTE mismatch between the matrix and the second phase (Cu6Sn5 and TiO2), and (iv) the load-bearing effects due to the presence of nano-sized reinforcements.
The effects of nano-Al2O3 on the microstructure and microhardness of the Sn3.5Ag0.5Cu composite solder alloy were studied. Compared with solder without addition, the formation of primary beta-Sn ...phase, the Ag3Sn phase average size, and the spacing lamellae decreased significantly in the composite solder matrix. In addition, the eutectic areas of the composite solder were wider than that of the Sn3.5Ag0.5Cu solder, due to the adsorption of nano-Al2O3 particles with high surface free energy on the grain surface during solidification. The wettability was improved by 0.25-0.5 wt% addition of nano-Al2O3 particles into the Sn3.5Ag0.5Cu solder. However, nano-Al2O3 particle concentration > 1.0 wt% decreased the beneficial influence. Microhardness improved with the addition of nano-Al2O3 particles, due to the composite microstructure, which is close to the theoretical prediction from dispersion strengthening theory.
The corrosion behavior of Cu-Sn intermetallics was investigated in 3.5 wt.% NaCl solutions and compared to that of Cu and Sn by using galvanic corrosion and polarization methods. Polarization curves ...showed that an increase in the Cu content increased the corrosion current density and shifted both corrosion potential and breakdown potential towards more noble values. The corrosion products on the surface of Sn, Cu and Cu sub(3)Sn were Sn sub(3)O(OH) sub(2)Cl sub(2), CuCl, and co-existing phases CuCl and Sn sub(3)O(OH) sub(2)Cl sub(2), respectively. In addition, the SnO sub(2), Sn sub(3)O(OH) sub(2)Cl sub(2), Cu sub(2)O, and CuCl sub(2) times sub(3)Cu(OH) sub(2) were observed in the Cu sub(6)Sn sub(5) phase.
Iron- and steel-making industry is one of the most water-intensive industries. An industrial wastewater purification plant using ultrafiltration and reverse osmosis is utilized by the iron and steel ...production industry to reclaim wastewater from the manufacturing processes. After sustained operation, the ultrafiltration membranes suffered from severe fouling problems. The frequent and necessary chemical cleaning results in raised operating cost, reduced permeate, and shortened membrane lifetime. The objective of this research was to identify the major foulants that result from long-term real-world operation of the ultrafiltration system. The fouled ultrafiltration membrane samples were collected four times during a 1.5-year period. Scanning electron microscope with energy-dispersive spectrometer, loss on ignition, and fouling resistance analysis were conducted to characterize the foulants. We identify iron (Fe) and manganese (Mn) oxides as the major foulants on the membrane surface and in the pores. We also demonstrate that irrecoverable fouling as the major contributor to fouling resistance, accounting for approximately 43 ~ 47% of the total increase in resistance. Based on our data, the irrecoverable fouling likely begins with the deposit of Fe and Mn ions and oxide particulates within the membrane pores, following by accumulation of additional oxides in part through an autocatalytic process, which ultimately leads to pore clogging. Therefore, pretreatment of the ultrafiltration influent to remove Fe and Mn ions can be a sound strategy to mitigate irrecoverable fouling.
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