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We report a systematic study of thecontrolled formation of discrete-sizedgold nanoparticle clusters (GNCs) by interaction with the reducingagent dithiothreitol (DTT). Asymmetric-flow field flow fractionationand electrospray differential mobility analysis were employed complementarilyto determine the particle size distributions of DTT-conjugated GNCs(DTT–GNCs). Transmission electron microscopy was used to providevisualization of DTT–GNCs at different states of aggregation.Surface packing density of DTT and the corresponding molecular conformationon the Au surface were characterized by inductively coupled plasmamass spectrometry and X-ray photoelectron spectroscopy. Results showthat DTT increases the aggregation rate of gold nanoparticles (AuNPs)up to ≈100 times. A mixed conformation (i.e., combining verticallyaligned, horizontally aligned, and cross-linking modes) exists forDTT on the Au surface for all conditions examined. The primary sizeof AuNPs, concentration of DTT, and the starting concentration ofAuNPs influence the degree of aggregation for DTT–GNCs, indicatingthat the collision frequency, energy barrier, and surface densityof DTT are the key factors that control the aggregation rate. DTT–GNCsexhibit improved structural stability compared to the citrate-stabilizedGNCs (i.e., unconjugated) following reaction with thiolated polyethyleneglycol (SH-PEG), indicating that cross-linking and surface protectionby DTT suppresses disaggregation normally induced by the steric repulsionof SH-PEG. This work describes a prototype methodology to form ligand-conjugatedGNCs with high-quality and well-controlled material properties. [ABSTRACT FROM AUTHOR]

An electrospray–differentialmobility analyzer (ES-DMA)was operated with an aerosol flow-mode, temperature-programmed approachto enhance its ability to characterize the particle size distributions(PSDs) of nanoscale particles (NPs) in the presence of adsorbed andfree ligands. Titanium dioxide NPs (TiO2-NPs) stabilizedby citric acid (CA) or bovine serum albumin (BSA) were utilized asrepresentative systems. Transmission electron microscopy (TEM) andinductively coupled plasma mass spectrometry were used to providevisual information and elemental-based PSDs, respectively. Resultsshow that the interference resulting from electrospray-dried nonvolatilesalt residual nanoscale particles (S-NPs) could be effectively reducedusing the thermal treatment process: PSDs were accurately measuredat temperatures above 200 °C for CA-stabilized TiO2-NPs and above 400 °C for BSA-stabilized TiO2-NPs.Moreover, TEM confirmed the volumetric shrinkage of S-NPs due to thermaltreatment and also showed that the primary structure of TiO2-NPs was relatively stable over the temperature range studied (i.e.,below 700 °C). Conversely, the shape factor for TiO2-NPs decreased after treatment above 500 °C, possibly due toa change in the secondary (aggregate) structure. S-NPs from BSA-stabilizedTiO2-NPs exhibited higher global activation energies towardinduced volumetric shrinkage than those of CA-stabilized TiO2-NPs, suggesting that activation energy is dependent on ligand size.This prototype study demonstrates the efficacy of using ES-DMA coupledwith thermal treatment for characterizing the physical state of NPs,even in a complex medium (e.g., containing plasma proteins) and inthe presence of particle agglomerates induced by interaction withbinding ligands. [ABSTRACT FROM AUTHOR]

Dithiothreitol (DTT)-based displacement is widely utilized for separating ligands from their gold nanoparticle (AuNP) conjugates, a critical step for differentiating and quantifying surface-bound functional ligands and therefore the effective surface density of these species on nanoparticle-based therapeutics and other functional constructs. The underlying assumption is that DTT is smaller and much more reactive toward gold compared with most ligands of interest, and as a result will reactively displace the ligands from surface sites thereby enabling their quantification. In this study, we use complementary dimensional and spectroscopic methods to characterize the efficiency of DTT displacement. Thiolated methoxypolyethylene glycol (SH-PEG) and bovine serum albumin (BSA) were chosen as representative ligands. Results clearly show that (1) DTT does not completely displace bound SH-PEG or BSA from AuNPs, and (2) the displacement efficiency is dependent on the binding affinity between the ligands and the AuNP surface. Additionally, the displacement efficiency for conjugated SH-PEG is moderately dependent on the molecular mass (yielding efficiencies ranging from 60 to 80 % measured by ATR-FTIR and ≈90 % by ES-DMA), indicating that the displacement efficiency for SH-PEG is predominantly determined by the S-Au bond. BSA is particularly difficult to displace with DTT (i.e., the displacement efficiency is nearly zero) when it is in the so-called normal form. The displacement efficiency for BSA improves to 80 % when it undergoes a conformational change to the expanded form through a process of pH change or treatment with a surfactant. An analysis of the three-component system (SH-PEG + BSA + AuNP) indicates that the presence of SH-PEG decreases the displacement efficiency for BSA, whereas the displacement efficiency for SH-PEG is less impacted by the presence of BSA. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this study, a prototypical thiolated organic ligand, 3-mercaptopropionic acid (MPA), was conjugated on gold nanoparticles (AuNPs), and packing density was measured on an ensemble-averaged basis using inductively coupled plasma optical emission spectrometry. The effects of sample preparation, including centrifugation and digestion, as well as AuNP size and concentration, on recovery were investigated. For AuNPs with diameters of 5, 10, 30, 60, and 100 nm, calculated packing density is independent of size, averaging 7.8 nm and ranging from 6.7 to 9.0 nm, and is comparable to reported values for MPA and similar short-chain ligands on AuNPs. These preliminary data provide fundamental information on the advantages and limitations of ICP-based analyses of conjugated AuNP systems. Moreover, they provide necessary information for the development of more broadly applicable methods for quantifying nanoparticle-ligand conjugates of critical importance to nanomedicine applications. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We report a case of a patient on maintenance peritoneal dialysis therapy treated with a high-dose methotrexate regimen for central nervous system lymphoma. For the initial methotrexate cycles, he had received temporary daily high-flux hemodialysis starting 24 hours after the infusion of methotrexate to avoid toxicity. However, on account of issues with vascular access, he was treated with continuous multiple-exchange peritoneal dialysis for the last 2 cycles of chemotherapy. Time-averaged clearances (dose divided by area under the curve, combination of endogenous and dialysis clearance) during treatment with high-flux hemodialysis and continuous multiple-exchange peritoneal dialysis were 0.77 mL/min/kg (0.013 mL/s/kg) and 0.65 mL/min/kg (0.011 mL/s/kg), respectively. Peritoneal clearance of methotrexate was estimated to be 0.124 +/- 0.037 mL/min/kg (0.00207 +/- 0.00062 mL/s/kg). Despite lower clearance by means of peritoneal dialysis compared with hemodialysis, the patient did not develop clinical evidence of methotrexate toxicity. Copyright © 2009 National Kidney Foundation, Inc. [ABSTRACT FROM AUTHOR]

The effect of two auxin antagonists, 2,3,5-triiodobenzoic acid (TIBA) and 2- (p-chlorophenoxy)-2-methyl propionic acid (CMPA) on IAA-induced ethylene production in etiolated mung bean hypocotyl (Vigna radiata L. Rwilez cv. Berken) segments was studied. Both TIBA and CMPA inhibited IAA-induced ethylene production and CO2 production at concentrations from 0.001 mM to 0.1 mM to 1.0 mM, respectively. The optimum concentration for inhibition of ethylene production by TIBA and CMPA, there was a significant decrease in IAA-induced ethylene production without a decrease in respiration rates below control levels. After 18 h, mung bean hypocotyl segments treated with 0.05 mM TIBA for 6 h or 0.5 mM CMPA for 8 h showed a maximum inhibition of IAA-induced ethylene production. Treatments longer than 8 h caused no further inhibition. The uptake of [14C]- napthaleneacetic acid by mung bean segments was greatly reduced by the addition of either TIBA (0.05mM) or CMPA (0.5 mM) to the incubation media. The result of treatment sequences showed that TIBA needed to be applied prior to IAA in order to inhibit IAA-induced ethylene production, but CMPA caused the same inhibitory effect whether applied before or after IAA treatment. These findings provide evidence that TIBA inhibits auxin-induced ethylene production in etiolated mung bean hypocotyl segments by blocking auxin movement into the tissue whereas CMPA may work on both transport and location. [ABSTRACT FROM AUTHOR]

Brassinosteroid, an analogue of brassinolide, (BR) (2α, 3α, 22β, 23β‐tetrahydroxy‐24β‐methyl‐B‐homo‐7‐oxa‐5α‐cholestan‐6‐one), was tested in conjunction with indole‐3‐acetic acid (IAA), naphthaleneacetic acid (NAA), 2,4‐dichlorophenoxyacetic acid (2,4‐D), indole‐3‐butyric acid (IBA), indole‐3‐propionic acid (IPA), indole‐3‐pyruvic acid (IPyA), indole‐3‐aldehyde (IAld), indole‐3‐carbinol (ICB) or tryptophan (TRP) for its effects on ethylene production by etiolated mung bean (Vigna radiata (L.) Rwilcz cv. Berken) hypocotyl segements. The enhancement of ethylene production due to BR was greatest in conjunction with 1 μM IBA, 2,4‐D, IAA, or NAA (these increases were 2580, 2070, 890, and 300%, respectively). When increasing concentrations of IBA, 2,4‐D, IAA, or NAA were used, there was a decrease in the percentage stimulation by BR. Both IPyA and IPA had different optimal concentrations than the other auxins tested. Their BR‐enhanced maximum percentage stimulations (1430 and 1580%) were greatest with 5 μM IPya and 10 μM IPA, respectively. There was a marked reduction in the percentage stimulation by BR with either 100 μM IPyA or IPA. The inactive indoles (IAld, ICB, or TRP) did not synergize with BR at any of the concentrations tested. Four hours following treatment those segments in contact with 1 μM BR with or without the addition of 10 μM IAA began to show a stimulation in ethylene production above the control and this stimulation became greater over the following 20 h. It was necessary for BR to be in continual contact with the tissue to have a stimulatory effect on auxin‐induced ethylene production. When segments excised from greater distances below the hypocotyl hook, were treated with either IAA alone or in combination with BR, there was a decrease in ethylene production with increasing distance. There was no effect of hypocotyl length on BR stimulation of auxin‐induced ethylene production; however, there was a definite decrease in ethylene production when IAA was applied alone. [ABSTRACT FROM AUTHOR]

A novel method combining microfluidic-based synthesis and hyphenated electrospray-differential mobility analysis has been developed for the controlled crosslinking and simultaneous analysis of hydrogels. This approach has been successfully applied to the synthesis of hyaluronic acid hydrogels with precise particle size distributions. [Display omitted] This study presents a novel approach for the controlled synthesis and real-time characterization of crosslinked hyaluronic acid (HA) hydrogels utilizing a microfluidic platform coupled with hyphenated electrospray-differential mobility analysis (ES-DMA). By precisely controlling key synthesis parameters within the microfluidic environment, including pH, temperature, reaction time, and the molar ratio of HA to crosslinker (1,4-butanediol diglycidyl ether, BDDE), we successfully synthesized HA hydrogels with tailored size and properties. The integrated ES-DMA system provides rapid, in-line analysis of hydrogel particle size and distribution, enabling real-time monitoring and optimization of the synthesis process. Furthermore, small-angle x-ray scattering (SAXS) was employed to complement ES-DMA analysis, providing valuable insights into the internal structure and extent of crosslinking within the synthesized hydrogels. The evolution of the number-based particle size distribution revealed a strong correlation with the synthesis conditions, demonstrating the high degree of controllability achieved by this integrated approach. This novel methodology offers a promising platform for the high-throughput synthesis of uniform and well-defined hydrogel nanoparticles with enhanced traceability, paving the way for advancements in various applications including drug delivery, tissue engineering, and biomaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] • First-time successful calcium looping-integrated methane bi-reforming is achieved. • High-performance Pd-Ni-CaO-based dual functional material by aerosol synthesis. • First-time elucidation of the proposed CaL-BRM using density functional theory. Integration technology of methane bi-reforming (BRM; a combination of methane steam and dry reforming) with calcium looping (CaL-BRM) offered a novel solution to reduce CO 2 emission, enabling direct capture and conversion of low-concentration CO 2 from sources into value-added products (H 2 , syngas) within the same reactor. In this study, Ni-CaO-based dual-functional material (DFM), with a small quantity of palladium in the nanostructure, was developed via a continuous two-stage aerosol process and employed in the CaL-BRM. Experimental results demonstrate that Pd-Ni-CaO exhibited high activity and cyclic stability over multiple cycles, maintaining effective CO 2 capture (12.0 mmol CO2 /g CaO) and BRM performance (>98 % CO 2 conversion; H 2 /CO = 2) at a relatively low temperature (600 °C). Density functional theory calculations reveal that the presence of Pd lowered the activation energy of CH* dissociation, the rate-determining step, from 1.14 to 0.67 eV. The higher adsorption energy (−0.87 eV) of H 2 O on the Ni-Pd surface and the lower energy barrier (0.62 eV) for subsequent dissociation contributed to the promising catalytic performance in the presence of steam. These findings underscore the significance of utilizing appropriate DFM and demonstrate the potential of CaL-BRM for efficient integrated carbon capture and utilization. [ABSTRACT FROM AUTHOR]

The classical economic production quantity (EPQ) model assumes that items produced are of perfect quality and the production rate is constant. However, production quality depends on the condition of the process. Due to process deterioration or other factors, the production process may shift and produce imperfect quality items. These imperfect quality items sometimes can be reworked and repaired; hence, overall production-inventory costs can be reduced significantly. In addition, it can be found in practice that the time or cost required to repetitively produce a unit of a product decreases when the number of units produced by a worker or a group of workers increases. Under this circumstance, the unit production cost cannot be regarded as constant and, therefore, cannot be ignored when taking account of the total cost. This paper incorporates the effects of learning and the reworking of defective items on the EPQ model since they were not considered in existing models. An optimal operation policy that minimizes the expected total cost per unit time is derived. A numerical example is provided to illustrate the proposed model. In addition, sensitivity analysis is performed and discussed.

Copper foil, a thin layer of high-purity metallic copper, having excellent conductivity, ductility, and corrosion resistance, is extensively applied in various electronic applications. Thiolated (SH-containing) chemical additives (i.e., accelerator and inhibitor) in copper electroplating solution are known to be critical for optimizing the copper foil manufacturing processes. Due to the high ionic strength and acidity of copper electroplating solution, proper and accurate characterization of the thiolated chemical additives is a critical concern. In this study, a facile, accurate approach is developed for quantitative characterization of thiolated additives in the copper electroplating solution. Firstly, gold nanoparticles (AuNPs) were employed as an adsorbent for separating the thiolated chemical additives, namely, poly(ethylene glycol) methyl ether thiol (PEG-SH) as inhibitor, and 3-mercaptopropionic acid (MPA) as accelerator from other interfering chemicals present in the copper electroplating solution. Subsequently, quantitative analysis of the AuNPs in the form of thin particle film was performed using attenuated total reflection-Fourier transform infrared spectroscopy. Electrospray-differential mobility analyzer was employed orthogonally for the quantitative analysis of the amount of thiolated additives adsorbed on AuNP. Interestingly, the results indicated that the detection concentration ranges of 5 μM–100 μM for PEG-SH and 10 μM–200 μM for MPA, respectively. Overall, this work demonstrates a successful separation and analysis methodology for the thiolated chemical additives in copper electroplating solution which enables the precise control over the copper foil manufacturing process. [Display omitted] • The first study of successful quantifying thiolated additives in Cu electroplating solution. • Successful separation of targeting thiols from interferences in Cu electroplating solution. • Ultralow detection limit (5 μM) in high ionic and acidic conditions is achieved. [ABSTRACT FROM AUTHOR]