Interactions of inorganic oxide nanoparticles with sewage biosolids

The use of nanoparticles (NPs) in manufacturing continues to increase despite the growing concern over their potential environmental and health effects. Understanding the interaction of NPs and sewage sludge is crucial for determining the ultimate fate of NPs released to municipal wastewater treatment plants (WWTPs) as those interactions will determine whether the bulk of the material is retained in the sludge or released in the effluent stream. Analyzing the affinity of aluminum oxide, cerium oxide, and silicon oxide NPs, which are commonly used in semiconductor manufacturing processes, for biosolids used in municipal WWTPs provides a basis for estimating their removal efficiency. Batch studies were performed and the NPs were shown to partition onto the cellular surface. At the maximum equilibrium values tested (75-92 mg nanoparticles/L), the concentration of Al(2)O(3), CeO(2) and SiO(2) associated with the sludge was 137, 238, and 28 mg/g-sludge VSS, respectively. These results suggest that electrostatic interactions play a major role in determining NP association with biosolids.     

LaMer diagram approach to study the nucleation and growth of Cu2O nanoparticles using supersaturation theory

Uptake to cuprous oxide (Cu₂O) nanoparticle synthesis with various particle sizes and shapes via supersaturation chemistry approach (LaMer model) has been conducted. Ascorbic acid and maltodextrine as reducing agents and polyvinylpyrrolidone (PVP) as a surfactant were utilized for synthesis of Cu₂O nanoparticles in aqueous solution. The narrow particle size range was achieved by controlling the kinetics of nucleation and growth of particles to satisfy LaMer theory. This mean was performed utilizing different reducing agents (ascorbic acid and maltodextrin) and also, changing the reducing agent addition condition. The results showed the reducing agent addition condition, varying the size of Cu₂O nanoparticles from 89 nm to 74 nm for drop-wisely and at-once routes, respectively. The samples were characterized by XRD, SEM, and UV-Vis spectroscopy. The results indicate the shape of as-prepared cuprous oxide nanoparticles have close relationship with thermodynamic and kinetic conditions, and also reducing addition condition.     

The sequence of precipitation in the Al-Mg-Si-Cu alloy AA6111

The preciptation behavior of the aluminum alloy AA6111 in the advanced stages of aging has been studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM). The results have demonstrated the formation of various precipitate types and morphologies of quaternaryQ phase andβ (Mg₂Si) families at the peak-aged condition and during overaging at different temperatures. The work has clarified the sequence ofQ phase formation and showed evidence for a new morphology of this phase. The sequence of precipitation in AA6111 is elaborated in light of the new findings.     

Oxidation of organic impurities in the recycle and reclaim loops of ultra-pure water plants

 The oxidation of trace organic impurities in ultrapure water by ultraviolet light (UV), ozone, and the combination of UV/ozone is investigated. The emphasis is on the development of a global model to simulate the process that take place in the typical oxidation reactors used in ultrapure water plants. The study also focuses on reaction mechanism for oxidation of multi-component organic impurities. Eighteen organic model compounds are chosen as representative contaminants. The results demonstrate and confirm a significant synergistic effect between UV and ozone oxidation. A mechanism for the synergistic oxidation of organic impurities is proposed and validated with experimental data. The combination of the reaction and the reactor models is used to determine the fundamental kinetic parameters involved in the three oxidation processes. Received: 3 July 1998 / Accepted: 4 September 1998     

Mechanisms for synergistic oxidation of organics in ultrapure watersystems

A mechanistic model is developed for the distribution, oxidation, and removal of organic impurities in typical polishing loops of ultrapure water (UPW) plants. The model is applied to the case of the oxidation of organics by ultraviolet (UV), ozone, and a unique method of adding ozone to the UV unit. The model is validated with direct experimental measurements using various oxidation tests. In particular, the accumulation problem related to the recalcitrant (hard to remove) impurities in the UPW systems with recycle is explained. The model is also used to analyze the dynamic behavior of polishing and reclaim/recycle loops. The results show the potential oscillatory behavior of UPW loops in case of impurity surges. This behavior is important and needs to be prevented to avoid metrology and control problems     

Global ESRD Costs Associated with a Short Daily Hemodialysis Program in the United States

In spite of the growing evidence that daily hemodialysis (DHD) improves clinical outcomes and quality of life, the additional dialysis costs are not currently reimbursed in the United States. Nor have there been reports of the effects of DHD on end-stage renal disease (ESRD) global costs, which would help predict the financial impact of DHD on the ESRD program. Since 1996, 22 patients (20 in-center, 2 home) have switched from conventional thrice-weekly dialysis to short, daily dialysis with six treatments per week. Eighteen patients started for medical indications, and four started for nonmedical reasons. Causes of ESRD were the following: diabetes mellitus (6), hypertension (4), glomerulonephritis (6), hereditary (2), and other (4). Mean age was 56 ± 16 years. Patients had an average of 3.3 major comorbidities. Weekly conventional HD dialysis times were divided into six DHD treatments, each 2.0 ± 0.3 hours. Weekly Kt/V remained unchanged. Twenty-two patients were followed on DHD for 220 patient-months: 7 patients died after 1.8 ± 1.3 months, 2 were transplanted at 4.3 ± 3.2 months, and 2 discontinued DHD at 3.6 ± 4.8 months. Eleven patients remain on DHD at 17.4 ± 8.3 months. Actual costs per extra dialysis session are as follows: $14.30 for supplies and $3.20 for labor for setup/cleanup time (15 minutes at $12.80/hour). Annualized DHD savings are based on comparison of doses of epoetin alpha (Epogen) and blood pressure medication at the start and after 12 months of DHD. Hospitalization rates include all enrolled patients, comparing rates for the 12 months prior to DHD with the first year on DHD, or annualized rates for those on DHD less than one year. Cost assumptions are $9/ 1000 U Epogen, $1/blood pressure pill, and $1200/per day of hospitalization. Extra transportation costs were covered by the patients. No increased access problems were observed. For patients on short DHD longer than 12 months, supply and labor costs increased to $2733/patient/year; however, Epogen use was reduced 55%, and blood pressure medications were reduced 40%. For all patients who switched to DHD, hospitalization rates were reduced 24%. This resulted in a net savings of about $4241/patient/ year after 12 months on DHD. Overall ESRD costs were substantially decreased on DHD. These cost savings must be passed on to providers before DHD becomes more widely available.     

Adaptive Immune Responses in a Multiple Sclerosis Patient with Acute Varicella-Zoster Virus Reactivation during Treatment with Fingolimod

Fingolimod, an oral sphingosine 1-phosphate (S1P) receptor modulator, is approved for the treatment of relapsing forms of multiple sclerosis (MS). The interference with S1P signaling leads to retention particularly of chemokine receptor-7 (CCR7) expressing T cells in lymph nodes. The immunological basis of varicella zoster virus (VZV) infections during fingolimod treatment is unclear. Here, we studied the dynamics of systemic and intrathecal immune responses associated with symptomatic VZV reactivation including cessation of fingolimod and initiation of antiviral therapy. Key features in peripheral blood were an about two-fold increase of VZV-specific IgG at diagnosis of VZV reactivation as compared to the previous months, a relative enrichment of effector CD4+ T cells (36% versus mean 12% in controls), and an accelerated reconstitution of absolute lymphocytes counts including a normalized CD4+/CD8+ ratio and reappearance of CCR7+ T cells. In cerebrospinal fluid (CSF) the lymphocytic pleocytosis and CD4+/CD8+ ratios at diagnosis of reactivation and after nine days of fingolimod discontinuation remained unchanged. During this time CCR7+ T cells were not observed in CSF. Further research into fingolimod-associated VZV reactivation and immune reconstitution is mandatory to prevent morbidity and mortality associated with this potentially life-threatening condition.     

Utilization of coal-ash minerals for technological ceramics

Glasses synthesized from Utah bituminous coal-ash melts were crystallized to form glass ceramics to determine the feasibility of coal-ash utilization. The use of additives to promote glass formation and catalysts to serve as nucleation sites for crystallization was studied. The microstructure of the crystalline phase was investigated using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The bulk glasses and glass-ceramics were evaluated by Knoop microhardness and density measurements. The crystalline phase formed has been identified as anorthite, CaAl₂Si₂O₈. Crystallization of the ash was possible up to a maximum of approximately 40%. The use of TiO₂ as a nucleation catalyst did little to improve the degree of crystallinity; however, the crystal phase became better defined when this catalyst was used, even in small amounts.     

Preparation and Characterization of Nanocrystalline Misch-Metal-Substituted Yttrium Iron Garnet Powder by the Sol–Gel Combustion Process

Nanocrystalline Y_{3− x} MM _x Fe₅O₁₂ powders (MM denotes Misch-metal, x =0.0, 0.25, 0.5, 0.75, and 1.0) were synthesized by a sol–gel combustion method. Magnetic properties and crystalline structures were investigated using X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscope. The XRD patterns showed that the single-phase garnet of Y_{3− x} MM _x Fe₅O₁₂ was formed at x values ≤1.0. The saturation magnetization of powders increased with decreasing MM content and reached the maximum value at Y₃Fe₅O₁₂. The crystallite size of powders calcined at 800°C for 3 h was in the range of 38–53 nm.