Large Size Distribution Research Articles

Sonochemical-assisted synthesis of highly stable gold nanoparticles catalyst for decoloration of methylene blue dye

Gold nanoparticles (AuNPs) can be easily synthesised using several methods for various applications in the industrial and medical sectors. However, their performance as a catalyst has not yet to be appropriately studied and optimised due to large size distribution and high agglomeration property. In this work, AuNP were synthesized by a sonochemical method using sodium citrate as a reducing agent and capping material. A Vibra-Cell ultrasonic solid horn with a half-inch tip size, frequency of 20 kHz and different ultrasound output powers (12, 20 and 36 W) was used in the synthesis. The as-synthesized AuNPs exhibited a spherical morphology with smooth geometry, excellent stability and high monodispersity after 10 min of sonication. AuNPs sizes decreased with increased sonication output power, which implies that the particle size, surface plasmon resonance, stability and monodispersity of the AuNPs depended on ultrasound output power and reaction time. Overall, this study showed that the sonochemical synthesis of AuNPs was an easy and controllable approach and can be potentially applied to fabricate other nanosized particles. AuNP's catalytic efficiency for the degradation of methylene blue has a fast decoloration rate of about 10 min.

Mathematical modelling of reaction-separation in an enzymatic membrane reactor during oligodextran production

Producing oligodextran with an enzymatic membrane reactor (EMR) is a promising alternative to traditional fermentation processes due to its high efficiency and environmental compatibility. Process analysis and optimization of an EMR system used for producing oligodextran are critical to improving EMR operating stability and cost effectiveness. We herein developed a mathematical model to evaluate the effects of operating conditions and membrane properties on the reaction-separation behavior of an EMR. Our analysis shows that tailoring a membrane with large porosity and uniform pore size distribution can simultaneously improve the product quality and production efficiency. The optimal parameters of operating pressure and agitation speed for achieving high production efficiency depend on the selection of operating mode. EMR prefers higher operating pressure to increase the production efficiency under water feeding mode. However, since the membrane suffered severer fouling under substrate feeding mode, the extensive agitation is required to inhibit membrane fouling and enhance production yield. Our work paves a new avenue towards the fundamental understanding and designing of highly effective and low consumptive EMR for oligodextran production.

Preparation of Healthy Mayonnaise by Using Plant and Animal Gums as Oil Replacer

Mayonnaise is an appetizer common in Iraq, and the demand for it has increased in recent times with the trend of the societies towards fast food and prepared foods. Therefore, this study was conducted to reduce the number of calories in mayonnaise. The chitin was extracted from crab shells, where the acetyl groups were removed with an alkali treatment to prepare chitosan, tamarind gum was also extracted. The prepared hydrocolloids, represented by chitosan and tamarind gum at 3%, were used as a stabilizer, and fat replaces in the manufacture of reduced-fat mayonnaise (RFM) and light mayonnaise (LF) and was compared with full-fat mayonnaise (FFM). Thus, the quality of the prepared mayonnaise treatments was assessed by analyzing the chemical composition, and the caloric value. Furthermore, the physicochemical properties represented by (stability, heat stability, pH, and viscosity) were studied, and microscopy and sensory evaluation were performed. The results showed an increase in the moisture content of the mayonnaise treatments with a decrease in the percentage of fat, and that the caloric value of low-calorie mayonnaise decreased significantly in the treatments that had a lower fat percentage. Light mayonnaise LM1 (prepared with adding chitosan) and LM2 (prepared with the addition of tamarind gum seed) were observed to have a higher moisture content than FFM and generally, the moisture content increased with increasing the level of fat replacing. The caloric values of the treatments containing fat replacer were significantly decreased. Low-fat mayonnaise samples showed high stability. The highest stability values were obtained in the RFM1 (prepared by adding chitosan) and the lowest value of stability in the FFM. Slight significant differences were observed in the pH values between the treatments, and the pH value of FFM was less than the rest of the treatments. The optical microscope images in the samples of FFM showed that small droplets were efficiently packed between the larger ones, while in the RFM samples, larger size distributions and smaller droplets appeared. The treatment RFM1 obtained the highest mark for the sensory evaluation compared to the other treatments and the consistency values were affected by the viscosity of the mayonnaise treatments, as the higher viscosity value of the RFM1 treatment corresponded to the highest value of the consistency in the same treatment. It can be concluded from this research the possibility of using the chitosan and the tamarind gum as suitable replacers for the fat in preparing healthy, low-calorie mayonnaise, as they are healthy hydrocolloids, which are non-toxic, biodegradable, and easy to prepare steps, as they do not being caused an undesirable change in the specific properties of mayonnaise.

The Ongoing Impact of COVID-19 on US Dermatology Practices

Background: COVID-19 is significantly impacting healthcare delivery worldwide. Chen et al anecdotally reported the impact on dermatology outpatient care at the outbreak epicenter in Wuhan, China, but nothing has yet been assessed for the US. The purpose of this study was to determine the magnitude of the ongoing impact of COVID-19 on US dermatology outpatient care. Methods: After pre-validation, 2 surveys comparing outpatient volumes and scheduling issues for the weeks of February 17th versus the week of March 16th, 2020 (Survey 1) and April 13th, 2020 (Survey 2) and for estimation of trends in the next several weeks was emailed to 9,891 US Dermatologists on 3/21(Survey 1) and 4/18(Survey 2)(Tables S1a & S1b). Because of the importance of this information and the need for rapid dissemination, only data from the first 1,000 respondents (collected in the initial 36 hours) were included in each survey. In Survey 1, 30 responses were removed due to ineligible geography or errors in survey entry, leaving 970 for the analysis. Survey 2 consisted of 1,000 eligible respondents. Demographics (Table 1) representativeness with AAD membership was confirmed (Table S2). Statistical significance was calculated using chi-square, difference-of-proportions, and two-tailed independent t-tests. Results: COVID-19 impact was material (Table 2). From the 3rd week in February to the 3rd week in March to the 3rd week in April, the average number of patients seen fell from 149.4 to 63.4 to 28.2(p<0.0001), practice days from 4.2 to 3.1 and then rose to 3.5(p<0.0001) and biopsies from 19.8 to 7.7 to 3.5(p<0.0001). Although by 3/16 there were only 24.5k cases nationally, the early-phase decrease in patient volume and office days suggests the magnitude of disease concern impact was greater than actual prevalence. Postponement of non-essential appointments increased from 35.5% to 79.4% to 95.6%(p<0.00001). In Survey 1, 66.3% of respondents estimated a >50% decrease in patient volume in the coming 2 weeks (18.9% completely closing practices) and, disturbingly, 47.2% of respondents in the 2nd survey estimated an additional 50%+ decrease in patient volume in the next 2 weeks. 54.6% (Survey 1) of postponed appointments were for >4 weeks with an additional 25.4% not rescheduled. Discussion: A greater negative impact was found in US “hotspot” regions (36% (Survey 1) and 34% (Survey 2) of respondents-Figure S1) for week 3/16-20 for practice days (3.0 hotspots vs. 3.3 non-hotspots) and patients seen (56.2 in hotspots vs. 70.0 in non-hotspots); and for week 4/13-18 (3.4 in hotspots vs 3.5 in non-hotspots) and patients seen (25.3 in hotspots vs 29.7 in non-hotspots). No significant differing telemedicine usage (39.5% hotspots vs 37.2% non-hotspots) or practice closure (21.0% hotspots vs 17.6% non-hotspots) was found in Survey 1 (March); however, a significant difference in telemedicine usage (54.5% hotspots vs 45.5% non-hotspots) and practice closure (25.4% hotspots vs 16.4% non-hotspots, when compared to a typical April week) was found in Survey 2 (April). Mean estimated telemedicine visits overall for the next 2 weeks was 37.8% (Survey 1) and 45.9% (Survey 2). Academic/University/Institutional dermatologists were significantly more likely to use telemedicine (Survey 1=57.1%, Survey 2=68.6%) than private practitioners (Survey 1=35.5%, Survey 2=46.2%). Telemedicine usage was less likely for dermatologists with >30 practice years (>30=32.4% vs 40.0%) and this trend continued in April with only 37.2% of more experienced dermatologists using telemendine. However, telemedicine usage does not have an impact on the deferred/postponed biopsies that had already occurred during the March (mean=10.7) or April (mean=7.9) weeks as well as those predicted to be subsequently postponed. Limitations include that this study reflects a “snapshot” which could materially change given the dynamically evolving situation. Estimations could have led to recall bias and the 10.1% response rate could have introduced sampling and non-response bias. Those with lower work volumes could have been more likely to have time to respond, but this bias was minimized by weekend-only data collection. However, the large sample size and representative distribution mitigate selection bias and standard statistical testing demonstrated significance. Conclusion: Our findings demonstrate the significant early impact of COVID-19 on US dermatologic care and can help better understand national trends. With an estimated 49.9 million annual US dermatology office visits, the 50%+ decrease in predicted visits could be devastating. Beyond telemedicine, other innovative approaches will need to be developed and implemented to help delivery of essential dermatology care during this crisis.

A review of methods for the removal of penicillins from water

Penicillins (PENs) are β-lactam antibiotics with significant environmental toxicology. This review aimed to synthesise the research efforts on the removal of PENs via a variety of separation, degradation and biological processes. It was observed that isotropic microporous microfiltration membranes are not effective for rejecting PENs, due to their large uniform pore size distribution. Researchers favoured the application of Nanofiltration membrane and adsorption as separation technologies. Carbon-based adsorbents were the most efficient class of adsorbents for PENs removal from water. Lewis acid-base interactions, hydrogen bonding, electrostatic attraction and π – π interactions were the main adsorption mechanisms. Generally, the ultraviolet irradiation assisted-advanced oxidation processes (AOPs) and the Fenton-like processes outperformed the electrochemical and ultrasonic assisted-AOPs for PENs degradation. AOPs must be incorporated with other methods of treatment to minimise potential costs in terms of energy, time, equipment, and chemicals. For biological processes for PENs removal, anaerobic treatment processes were observed to be more efficient for the removal of PENs than aerobic processes. With the exception of microfiltration and electrocoagulation, most other processes were found to be effective for the removal of PENs from water, albeit with some disadvantages. From the review, it can be surmised that there has been great research progress on the subject and many new findings have been obtained in recent times though there is still much work to be done.

Phosphorus‐Functionalized Graphene for Lithium‐Ion Capacitors with Improved Power and Cyclability

AbstractHerein, we report an easy approach for the preparation of graphene‐based materials suitable as electrodes for lithium‐ion capacitors (LICs). To the best of our knowledge, this is the first time that phosphorus‐functionalized graphene oxide (rGO800‐P) is used as negative (battery‐type) electrode in LICs technology. An activated carbon derived from the pyrolysis of graphene‐carbon composite served as positive (capacitor‐type) electrode. While phosphorus functionalization on the negative electrode enables fast Li+ kinetics during insertion/extraction processes, the flat‐shaped morphology, large surface area and proper pore size distribution of the positive electrode enhance the double‐layer formation. Full LICs optimization, oversizing the negative electrode allows operating in the extended voltage window of 1.5–4.5 V delivering high energy and power values (91 Wh kg−1AM at 145 W kg−1AM and 33 Wh kg−1AM at 26,000 W kg−1AM) without compromising the cycling performance (76 % capacitance retention after 10,000 cycles).

Influence of Multidimensional Graphene Oxide (GO) Sheets on Anti-Biofouling and Desalination Performance of Thin-Film Composite Membranes: Effects of GO Lateral Sizes and Oxidation Degree.

The influence of the lateral size and the content of graphene oxide (GO) flakes in specific oxygenate functional groups on the anti-biofouling properties and performance of thin-film composite membrane (TFC) was studied. Three different multidimensional GO samples were prepared with small (500–1200 nm), medium (1200–2300 nm), and large (2300–3600 nm) size distribution, and with different degrees of oxidation (GO3 > GO2 > GO1), varying the concentration of the hydrogen peroxide amount during GO synthesis. GO1 sheets’ length have a heterogeneous size distribution containing all size groups, whilst GO2 is contained in a medium-size group, and GO3 is totally contained within a small-size group. Moreover, GO oxygenate groups were controlled. GO2 and GO3 have hydroxyl and epoxy groups at the basal plane of their sheets. Meanwhile, GO1 presented only hydroxyl groups. GO sheets were incorporated into the polyamide (PA) layer of the TFC membrane during the interfacial polymerization reaction. The incorporation of GO1 produced a modified membrane with excellent bactericidal properties and anti-adhesion capacity, as well as superior desalination performance with high water flow (133% as compared with the unmodified membrane). For GO2 and GO3, despite the significant anti-biofouling effect, a detrimental impact on desalination performance was observed. The high content of large sheets in GO2 and small sheet stacking in GO3 produced an unfavorable impact on the water flow. Therefore, the synergistic effect due to the presence of large- and small-sized GO sheets and high content of OH-functional groups (GO1) made it possible to balance the performance of the membrane.

Liquid‐phase preparation of BaTiO3nanoparticles

Barium titanate (BaTiO3, BT) is widely used in the manufacture of electronic components such as multilayer ceramic capacitors, supercapacitors, thermistors, ferroelectric devices and piezoelectric devices due to its excellent dielectric, ferroelectric, piezoelectric and insulating properties. The performance of BT-based components is highly dependent on the quality of the BT nanoparticles. Large particle size and uneven distribution are the disadvantages of the BT nanoparticles synthesised by the traditional solid-phase reaction, however, the liquid-phase method can overcome these shortcomings, which has the characteristics of high purity and uniform composition with small particle size, and therefore is the main method for the preparation of BT nanoparticles. This review described various liquid-phase preparation methods of BT nanoparticles and compared the advantages and disadvantages of these methods, thereafter the optimised process parameters that affected the BT crystalline quality were summarised so as to obtain BT nanoparticles with a high crystalline quality, small particle size and even distribution.

Achieving low-temperature Zr alloying for microstructural refinement of sand-cast Mg-Gd-Y alloy by employing zirconium tetrachloride

The large size and uneven distribution of Zr particles always lead to a high alloying temperature and low Zr yield when MgZr master alloy is used for grain refinement of sand-cast Mg-RE alloys. In this research, the feasibility of Zr alloying by applying ZrCl4 in sand-cast GW83 alloy at a low temperature (720 °C) was investigated. The interaction procedure between ZrCl4 and Mg melt, and corresponding grain refinement mechanisms were systematically studied by thermodynamic calculation, thermal analysis, and microstructure characterization. The results showed that the yield of Zr by applying ZrCl4 was higher than that of the MgZr master alloy. Zr can be generated via the in-suit reaction between ZrCl4 and Mg. Both the nucleation temperature and nucleation undercooling increased with the increasing addition of ZrCl4. The average grain size decreased from 832 μm to 229 μm with 2.606 wt% ZrCl4 addition due to the heterogeneous nuclei of Zr particles and the constitutional supercooling provided by solute Zr. A corresponding physical model depicting the solidification behavior and grain refinement mechanism was proposed. However, the ZrCl4 addition of 4.343 wt% led to a large amount of RECl3 inclusions generated during the Zr alloying process, deteriorating the mechanical properties of the alloy.

The Effect of Particle Size Distribution and Liberation Degree on the Separation Performance of Industrial Spirals in Low-grade Chromite Processing

Spirals, the most common equipment for the separation of heavy minerals such as chromite, are greatly affected by size distribution and the liberation degree (hence the specific gravity and size) of the feed particles. In this study, the efficiency of spirals in separation of low-grade chromite particles has been investigated by studying the distribution of grade, size distribution and liberation degree of feed, concentrate, and tailings of spiral. For this purpose, mass balance constraints were applied to the spiral-containing chromite processing circuit. Afterwards, the grade variations and size distributions have been investigated. According to the results, when the feed to the spiral has a larger size distribution, the enrichment ratio of the feed is 1.32 and, with the smaller feed size, this value has increased to 1.99. When the spiral feed has a larger size distribution and higher specific gravity, the recovery of chromite increases with increasing particle size up to 250 microns, and then with increasing particle size, recovery decreases with a relatively steep slope. Evaluation of spiral efficiency with respect to particle liberation degree has also shown that despite the high degree of liberation of spiral feed in size fractions smaller than 75 microns (88.9%), the liberation degree of spiral concentrate and tail in this faction is equal to and less than that of feed, which can indicate poor spiral performance in these size fractions.

Assessment of low-cost cartridge filters for implementation in household drinking water treatment systems

In regions where houses are sparsely located, traditional centralized water treatment plants are not economically feasible, with household water treatment (HWT) systems commonly used to provide potable water for a range of household activities. Filtration prior to disinfection is essential, and due to their ease of use and small footprint, cartridge filters are commonly employed. In this work, readily available commercial filter types (spun, wound and pleated) of different micron ratings (10, 5 and 1) were tested for the removal of turbidity either alone or in series via simulated large volume pilot trials. Water with an initial turbidity of 40 ± 10 NTU was prepared using fine test dust (ISO 12103-1, A2) with the turbidity removal efficiency, pressure drop, total capacity and lifespan of the filters evaluated.To increase useable filter lifetime upon reaching the 1 bar pressure limit, a series of washing steps were employed to regenerate the filters. Whilst pleated filters could be efficiently cleaned, spun and wound filters could not, and were discarded after single use. In pilot trials, the volume of turbid water filtered varied from 0.85 m3 with a 1 micron wound filter to 6 m3, with 5 and 1 micron pleated filters in series, which following regeneration could be used for three filtration cycles. For pleated filters, turbidity removal efficiency improved over time as a cake built up resulting in the effluent turbidity reaching acceptable quality (<5 NTU). This criterion continued to be achieved with repeated cycles of washed pleated filters, thereby significantly reducing the cost and improving sustainability of the HWT system. Field trials were carried out with a similar HWT system (5 and 1 micron spun filters) installed in households of rural communities in Curiti, Colombia. Turbidity was effectively removed from natural water (reduction to <1.2 NTU) with improved efficacy in comparison to synthetic water samples due to the large particle size distribution observed in the natural water.

Graphene Oxide Thin Films: Synthesis and Optical Characterization

AbstractThe oxidized derivative of graphene named Graphene oxide (GO) are attractive materials as optoelectronic devices due to their optical response in the mid‐infrared wavelength spectral range; however, very large‐scaled synthesis methods and optical characterization are required. Here, GO thin films are fabricated on quartz by implementing simple two‐step pyrolysis processes by using renewable bamboo as source material. The effect of carbonization temperature (TCA) on the compositional, vibrational, and optoelectronic properties of the system are investigated. It was found that as TCA increases, graphite conversion rises, oxygen coverage reduces from 17 % to 4 %, and the band‐gap energy monotonically decreases from 0.30 to 0.11 eV. Theoretical predictions of the energy band‐gap variations with the oxide coverage obtained via density functional theory (DFT) computational simulations agree well with the experimental results, providing evidence of oxygen‐mediated charge‐transport scattering. Interestingly, in the optical response, increased TCA results in a blue‐shift of the absorption and the absorbance spectrum can be correlated with the large size distribution of the graphitic nano‐crystals of the samples. These results suggest that graphene oxide‐bamboo pyroligneous acid (GO) thin films exhibit optoelectronic response useful in developing photodetectors and emitter devices in the mid‐infrared (MIR) spectral range.

New contributions to two ciliate genera (Ciliophora, Heterotrichea) based on morphological and molecular analyses, with description of a new Gruberia species

BackgroundHeterotrichous ciliates are common members of microeukaryote communities which play important roles in both the transfer of material and the flow of energy in aquatic food webs. This group has been known for over two centuries due to their large body size and cosmopolitan distribution. Nevertheless, species identification and phylogenetic relationships of heterotrichs remain challenging due to the lack of accurate morphological information and insufficient molecular data.ResultsThe morphology and phylogeny of two heterotrichous ciliates, namely Gruberia foissneri spec. nov. and Linostomella vorticella (Ehrenberg, 1833) Aescht in Foissner et al., 1999, were studied using rigorous methods (living morphology, stained preparations, and small subunit rDNA sequence data). Gruberia foissneri spec. nov. is morphologically very similar to G. uninucleata Kahl, 1932, however, it can be distinguished from the latter by having more ciliary rows (about 32 vs. about 20) and macronuclear shape (sausage-shaped vs. ellipsoid). Based on a combination of previous and present studies, an improved diagnosis of L. vorticella is supplied and several taxonomic anomalies are clarified. In addition, phylogenetic analyses based on SSU rDNA sequence data support the generic assignment of these two species.ConclusionsModern ciliate taxonomy should be performed by means of detailed living observation, stained preparations and molecular information. For those species that have been reported in previous studies, it is necessary to provide as much useful information as possible using state-of-the-art methods in order to resolve taxonomic anomalies.

The Angstrom exponents of black carbon aerosols with non-absorptive coating: A numerical investigation

Black carbon (BC) aerosols exert important effects on regional and global climate, whilst there still are significant uncertainties in their optical properties, particularly the spectral varying Angstrom exponents. This study numerically evaluates the influences of coating morphologies on optical properties of BC with non-absorbing coating, and evaluates the sensitivity of their Angstrom exponents, including extinction Angstrom exponent (EAE), absorption Angstrom exponent (AAE) and single scattering albedo Angstrom exponent (SSAAE), to particle microphysics with the multiple-sphere T-matrix method. Among all microphysical parameters, the shell/core ratio and size distribution play substantial roles in determining the EAE, AAE and SSAAE of coated BC, wherein the dependences of the Angstrom exponents on size distribution are higher. The EAE, AAE and SSAAE of coated BC by non-absorptive materials with different particle size distributions change in ranges of 0.3–1.5, 0.3–2.5 and –0.1–0.9, respectively. The core-shell Mie model can hardly produce accurate results of the Angstrom exponents of coated BC particles, especially the AAE and SSAAE. Our study reveals that BC coated by non-absorbing materials with large size distribution of coated BC may show negative SSAAE values for some coating microphysics, indicating the limitation of separating brown carbon from black carbon with a criterion of negative SSAAE.

Biotemplate synthesis of mesoporous α-Fe2O3 hierarchical structure with assisted pseudocapacitive as an anode for long-life lithium ion batteries

The oriented biotemplate synthesis of nanostructured metal oxides as anode materials for lithium-ion batteries (LIBs) has recently attracted widespread attentions. Herein, mesoporous α-Fe2O3 hierarchical tubes (named as Fe-400) were successfully prepared by facile iron salt impregnation and air calcination at 400 °C using waste poplar branch as biotemplate. The hierarchical structure of Fe-400 is constructed from cross-linked small nanoparticles (~29 nm), which then results in large specific surface area (37.7 m2 g−1) and uniform mesoporous size distribution (12.2 nm). As anode material for LIBs, Fe-400 displays reversible capacity of 880.7 mA h g−1 after long-cycle of 800th at 1 A g−1, indicating that this material has high capacity retention and good long-cycle stability. The prominent electrochemical properties are mainly ascribed to the large specific surface area, unique homogeneous mesopores, and the assisted pseudocapacitive behaviors of Fe-400. In view of the low-cost, environment-friendly and easily large-scale synthesis of Fe-400 electrode material, the present biotemplate strategy can present useful reference for the synthesis of other transition metal oxide-based anode materials for LIBs.

Reaction for the preparation of unique cyclic polysiloxanes with large size and narrow distribution

AbstractUtilizing collective forces between reactant and multiple catalyst molecules has been unprecedented due to the difficulty in realizing high order catalysis. Inspired by the power of collective forces in enzymes and organic catalysts, herein we report a rare example of high order catalysis for ring opening reaction (ROR) of strained rings by methanol. ROR is an important way to produce various polysiloxanes, but usually suffers from serious side reactions especially at high conversion, and currently there is a need to design new reaction pathway to achieve low molecular dispersity. In our study, the judiciously designed strained spiral cyclosiloxanes enable a high order catalysis by methanol, and this new methodology leads to a cyclic polysiloxane with high molecular weight and low dispersity even at full conversion of reactants. Kinetic study indicates an extremely unusual high‐order reaction involving multiple methanol molecules per reaction, also confirmed by quantum calculation which reveals the presence of zwitterionic ions stabilized by collecting force of hydrogen bonds by methanol molecules. The inherent driving force for this unusual phenomenon is dominated by enthalpy stabilization of the reactive intermediates through hydrogen bonding. The selective formation of SiOSi bonds, instead of silanol products, reflects the power of scientific design.

Climate-driven variability in Euphausia pacifica size distributions off northern California

We analyzed an 11-year data set of length measurements for Euphausia pacifica, resolved by developmental stages ranging from early furcilia through adults, to characterize temporal variability in size distributions in relation to environmental and climate forcing in coastal waters of the northern California Current. Our analysis reveals that coastal size distributions of this linchpin species are related to temperature and chlorophyll a concentration, and indicate that warm climate events disrupt and suppress typical seasonal dynamics, resulting in persistent shifts towards populations dominated by smaller juveniles and adults. The 2014-16 marine heatwave (MHW) resulted in sharp and sustained transition in the size structure of E. pacifica off northern California; we captured numerous mature individuals smaller than any previously reported in the literature and larger size classes were conspicuously absent or rare when the MHW most strongly impacted coastal waters. Early life history stages exhibited a contrasting response, shifting instead towards larger size distributions during warm years. Advection appears to be the dominant mechanism driving rapid shifts in E. pacifica size structure off northern California, which implies alongshore and cross-shelf gradients in life history expression (e.g., changes in size-at-maturation) related primarily to temperature. Variability in food availability (chlorophyll concentration) and physiological responses (e.g., changes in growth rates) likely contribute to seasonal variability, but appear insufficient to account for sharp, climate-driven transitions. Climate-driven shifts in individual and total biomass of this critical and dominant forage species have important ecological implications, particularly for growth and survival of species at higher trophic levels. Given that warm water events are likely to increase with climate change, the effects of the 2014-16 MHW on E. pacifica in coastal waters may serve as a harbinger for future change. Detailed information on size structure of euphausiid populations is fundamental to understanding population responses to and ecosystem consequences of climatic and environmental forcing, and has been incorporated in assessments that support ecosystem-based approaches to fisheries management.

Monodisperse and Water-Soluble Quantum Dots for SWIR Imaging via Carboxylic Acid Copolymer Ligands.

Compared to the visible and near-infrared, the short-wave infrared region (SWIR; 1000-2000 nm) has excellent properties for in vivo imaging: low autofluorescence, reduced scattering, and a low-absorption cross-section of blood or tissue. However, the general adoption of SWIR imaging in biomedical research will be enhanced by a broader availability of versatile and bright contrast materials. Quantum dots (QDs) are bright and compact SWIR emitters with narrow size distributions and emission spectra, but their use is limited by the shortcomings of established ligand systems for SWIR QDs. Established ligands often result in SWIR probes with either limited colloidal stability, large size, or broad size distribution or a combination of all three. We present a polymeric QD ligand designed to be compatible with oleate-coated QDs. Our polymeric acid ligand is a copolymer bearing carboxylic acid anchoring groups and PEG-550 chains to solubilize the QD-ligand construct. After a mild and rapid ligand exchange, the resulting constructs are compact (<11 nm hydrodynamic diameter) and have narrow size distribution. Both qualities are preserved for several months in isotonic saline. The constructs are bright in vivo, and to demonstrate their suitability for imaging, we perform whole-body imaging and lymphatic imaging, including visualization of lymphatic flow.

Improvements in the Organic-Phase Hydrothermal Synthesis of Monodisperse M x Fe3-x O4 (M = Fe, Mg, Zn) Spinel Nanoferrites for Magnetic Fluid Hyperthermia Application.

In the quest for optimal heat dissipaters for magnetic fluid hyperthermia applications, monodisperse MxFe3–xO4 (M = Fe, Mg, Zn) spinel nanoferrites were successfully synthesized through a modified organic-phase hydrothermal route. The chemical composition effect on the size, crystallinity, saturation magnetization, magnetic anisotropy, and heating potential of prepared nanoferrites were assessed using transmission electron microscopy (TEM), dynamic light scattering, X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), atomic absorption spectroscopy (AAS), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM) techniques. TEM revealed that a particle diameter between 6 and 14 nm could be controlled by varying the surfactant ratio and doping ions. EDS, AAS, XRD, and XPS confirmed the inclusion of Zn and Mg ions in the Fe3O4 structure. Magnetization studies via VSM revealed both the superparamagnetic nature of the nanoferrites and the dependence on substitution of the doped ions to the final magnetization. The broader zero-field cooling curve of Zn-doped Fe3O4 was related to their large size distribution. Finally, a maximum rising temperature (Tmax) of 66 °C was achieved for an aqueous ferrofluid of nondoped Fe3O4 nanoparticles after magnetic field activation for 12 min.

Early Characterization of NdFeB and NdFeB /Co-Al Composites of Sintering Using SPS

The purpose of this study is to obtain a permanent magnet end-product from NdFeB and NdFeB / Co-Al composite material from SPS sintering which has high density with small grain size and strong corrosion resistance. NdFeB powder and NdFeB/Co-Al composites (0.2 and 0.5weight%) of several micron-sized particles resulting from the milling process have been successfully sintered with a temperature parameter of 800°C for 10 minutes and a pressure of 50MPa in dies with a diameter of 20 mm in a vacuum chamber. Optical micrographs show that the grains are uniformly and smoothly distributed throughout the surface. This is showing the types of grain distributions which has good mechanical properties. The X-ray analysis result shows the phase analysis confirms the presence of such main PM phases as Nd, Fe and B. From SEM observation, the particles have irregular shapes and a large particle size distribution. The density value of the sample is in the range of 7.1 - 7.3. From the density measurement it is also known that the sintering sample with SPS has a high-density level which is close to 100%, so it can be said that it has formed fully dense.