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PubMed1997

Variability and uncertainty in spatial, temporal and spatiotemporal crop-yield and related data.

Application of the theories of precision agriculture to the practicalities of broad-acre farming relies on successful handling of the ramifications of uncertainty in information, i.e. information pertaining to the spatial and temporal variation of those factors which determine yield components and/or environmental losses. This paper discusses the uncertainty of yield and related variables as measured by their spatial and temporal variance. The magnitude of these two components gives a suggestion as to the appropriate scale of management. Simultaneous reporting on spatial and temporal variation is rare and the theory of these types of process is still in its infancy. Some brief theory is presented, followed by several examples from the Rothamsted classic experiments, yield-monitoring experiments in Australia, a long-term barley trial in Denmark, and a soil moisture monitoring network. It is clear that annual temporal variation is much larger than the spatial variation within single fields. This leads to the conclusion that if precision agriculture is to have a sound scientific basis and ultimately a practical outcome then the null hypothesis that still remains to be seriously researched is: 'given the large temporal variation in yields relative to the scale of a single field, then the optimal risk aversion strategy is uniform management.'

Crops, Agricultural↗

PubMed2006

Etiologic yield of autistic spectrum disorders: a prospective study.

Studies addressing etiologic yield in childhood developmental disabilities have mainly looked at individuals with developmental delay/mental retardation. The few studies addressing the question of etiologic yield in patients with pervasive developmental disorders (PDDs) had a major drawback, in that the enrolled subjects were diagnosed as having the autistic spectrum disorders based only on history and clinical examination, and/or on unspecified instruments. In addition, only some of these patients underwent a complete laboratory evaluation. To investigate the etiologic yield of PDDs, we undertook a large prospective study on subjects selected according to very strict criteria and diagnosed as having PDD based on the present "gold standard" (ADI-R and ADOS-G), and a clinical diagnosis made by a child psychiatrist. Eighty-five (85) patients with PDD and their first degree relatives participated in this study. These patients were selected from a sample of 236 subjects who had received a clinical diagnosis of PDD at the Stella Maris Institute between March 2002 and 2005. Selection criteria for entering the study were: (1) a diagnosis of PDD (with exclusion of the Rett syndrome) confirmed after the administration of the ADI-R (autism diagnostic interview-revised) and the ADOS-G (autism diagnostic observation schedule-generic). In addition, a clinical diagnosis was made by the child psychiatrist, on the basis of presence or absence of DSM-IV symptoms of autism; (2) chronological age between 4 and 18 years; (3) IQ>30; (4) availability of both biologic parents. Patients, 65/85 (76.5%), had autism, 18/85 (21.2%) had PDD-NOS, and the remaining 2/85 (2.3%) had Asperger syndrome. Ages varied between 4 years 2 months and 12 years 5 months (mean 7.6 years), and there was a marked male preponderance (68/85). All subjects underwent various laboratory studies and neuroimaging. With respect to possible etiologic determination, a detailed history and physical examination in this group of patients with PDD was informative in 10.5% (9/85). HRB karyotype was diagnostic in one, and molecular fragile X studies in one child. Brain MRI was informative in two children (2.3%) with relative macrocrania but no neurological features; and EEG was helpful in one child, identifying a Landau-Kleffner disorder. Audiometry and brainstem auditory evoked potentials (BAEPs) showed a bilateral sensorineural loss in another child. Metabolic evaluation gave normal results in all subjects. The results suggest an evaluation paradigm with reference to etiologic determination for individuals with PDDs that does not presently justify metabolic or neuroimaging on a screening basis. Recurrence risk, treatment implications, and significant and long-lasting emotional relief for the parents suggest that serious consideration be given to clinical genetic examination, genetic testing, EEG study (during wakefulness and sleep), and audiometry, despite a relatively low yield.

Adolescent↗

PubMed2003

Microalgae cultivation in air-lift reactors: modeling biomass yield and growth rate as a function of mixing frequency.

The slow development of microalgal biotechnology stems from the failure in the design of large-scale photobioreactors where light energy is efficiently utilized. Due to the light gradient inside the reactor and depending on the mixing properties, algae are subjected to certain light/dark cycles where the light period is characterized by a light gradient. These light/dark cycles will determine productivity and biomass yield on light energy. Air-lift reactors can be used for microalgae cultivation and medium-frequency light/dark cycles will be found in these systems. Light/dark cycles are associated with two basic parameters: first, the light fraction, i.e., the ratio between the light period and the cycle time and second, the frequency of the light/dark cycle. In the present work, light/dark cycles found in air-lift reactors were simulated taking into account the light gradient during the light period. The effect of medium-frequency cycle time (10-100 s) and light fraction (0.1-1) on growth rate and biomass yield on light energy of the microalgae Dunaliella tertiolecta was studied. The biomass yield and growth rates were mainly affected by the light fraction, while cycle time had little influence. Response surface methodology was used and a statistical model describing the effect of light fraction and cycle time on growth rate and biomass yield on light energy was developed. The use of the model as a reactor design criterion is discussed.

Biomass↗

PubMed2003

Improvement of the yield of physiologically active oligosaccharides in continuous hydrolysis of chitosan using immobilized chitosanases.

The continuous production of chitosan oligosaccharides using a packed-bed enzyme reactor was investigated as to the effects of the operation conditions on the yield of pentamers and hexamers of chitosan oligosaccharides. A column reactor packed with immobilized chitosanases prepared by the multipoint attachment method was used for continuous hydrolysis of chitosan. In this reactor, the decrease of the yield of the target intermediate oligosaccharides due to axial mixing was negligible. The surface enzyme density of the support and flow rate of the substrate solution significantly affected the maximum yield of pentamers and hexamers. These effects were summarized as a correlation with the Damköhler number (Da), defined as the ratio of the maximum reaction rate to the maximum mass transfer rate. The optimum condition was determined based on Da. Under the optimized condition (Da = 0.12), pentamers and hexamers could be produced continuously for a month with a yield of over 35% (7 kg/m(3) in concentration).

Bioreactors↗

PubMed2004

Estimating the potential refolding yield of recombinant proteins expressed as inclusion bodies.

Recombinant protein production in bacteria is efficient except that insoluble inclusion bodies form when some gene sequences are expressed. Such proteins must undergo renaturation, which is an inefficient process due to protein aggregation on dilution from concentrated denaturant. In this study, the protein-protein interactions of eight distinct inclusion-body proteins are quantified, in different solution conditions, by measurement of protein second virial coefficients (SVCs). Protein solubility is shown to decrease as the SVC is reduced (i.e., as protein interactions become more attractive). Plots of SVC versus denaturant concentration demonstrate two clear groupings of proteins: a more aggregative group and a group having higher SVC and better solubility. A correlation of the measured SVC with protein molecular weight and hydropathicity, that is able to predict which group each of the eight proteins falls into, is presented. The inclusion of additives known to inhibit aggregation during renaturation improves solubility and increases the SVC of both protein groups. Furthermore, an estimate of maximum refolding yield (or solubility) using high-performance liquid chromatography was obtained for each protein tested, under different environmental conditions, enabling a relationship between "yield" and SVC to be demonstrated. Combined, the results enable an approximate estimation of the maximum refolding yield that is attainable for each of the eight proteins examined, under a selected chemical environment. Although the correlations must be tested with a far larger set of protein sequences, this work represents a significant move beyond empirical approaches for optimizing renaturation conditions. The approach moves toward the ideal of predicting maximum refolding yield using simple bioinformatic metrics that can be estimated from the gene sequence. Such a capability could potentially "screen," in silico, those sequences suitable for expression in bacteria from those that must be expressed in more complex hosts.

Chromatography, High Pressure Liquid↗

PubMed2005

Improved yield of recombinant merozoite Surface protein 3 (MSP3) from Pichia pastoris using chemically defined media.

Plasmodium falciparum merozoite surface protein 3 (MSP3) is a leading blood-stage malaria vaccine candidate. Vaccination with Pichia pastoris derived recombinant MSP3 protected Aotus nacymai monkeys from the parasite's lethal challenge and the post-challenge antibody titer against MSP3 correlated with protection. In our preliminary attempts to produce this vaccine in fermentors, little or no expression of MSP3 was observed in chemically defined media, although the same P. pastoris strain produced MSP3 in complex media. Our goal is to develop a Phase I/II clinical manufacturing process in completely chemically defined media because of the concern of potential prion contamination in complex media containing animal derived products. Here, we report our investigations into various factors to improve the yield of MSP3 in defined media. We found that an induction pH (pH(i)) 6.8 yielded MSP3 at 434 mg/L whereas there was no product at pH(i)< or = 5, though cell growth was the same in all pH(i) levels examined. High levels of NH(4) (+) consumed at pH(i) 6.8 were directly correlated to the enhanced MSP3 production. Furthermore, an additional 3.5-fold increase in the yield of MSP3 was obtained by addition of casamino acids at pH(i) 6.8. No direct correlation was observed between protease activity in the culture supernatants and lack of MSP3 expression. Neither high P. pastoris biomass generated at a high specific growth rate (0.04/h) nor low induction temperatures during induction improved yield. Nitrogen source was the most important factor affecting expression of MSP3 in defined media.

Antigens, Protozoan↗

PubMed2006

Expanded thermodynamic model for microbial true yield prediction.

Thermodynamic methods to predict true yield and stoichiometry of bacterial reactions have been widely used in biotechnology and environmental engineering. However, yield predictions are often inaccurate for certain simple organic compounds. This work evaluates an existing method and identifies the cause of prediction errors for compounds with low degree of reductance of carbon. For these compounds, carbon, not energy or reducing equivalents, constrains growth. Existing thermodynamically-based models do not account for the potential of carbon-limited growth. The improved method described here consists of four balances: carbon balance, nitrogen balance, electron balance, and energy balance. Two efficiency terms, K1 and K2 are defined and estimated from a priori analysis. The results show that K1 and K2 are nearly the same in value so that only one coefficient, K = 0.41 is used in the modified model. Comparisons with observed yields show that use of the new model and parameters results in significantly improved yield estimation based on inclusion of the carbon balance. The average estimation error is less than 6% for the data set presented.

Bacteria↗

PubMed1976

Yield and maintenance relations of yeast growth in the chemostat at superoptimal temperatures.

A model is proposed that accounts for the decreases in yield which occur in chemostat cultures of mesophilic yeasts at superoptimal growth temperatures. Two yield depressing effects were identified, one due to increased maintenance requirements by the viable fraction of the population, the other due to energy substrate dissipation by the nonviable function. The two effects are functions of the dilution rate, as is the fraction of nonviable cells. Experimental results were obtained on the yield, maintenance, and dissipation of energy substrate in a glucose-limited chemostat culture of a respiration-deficient mutant of Saccharomyces cerevisiae at 39 degrees C. The rates of glucose utilization for maintenance and for dissipation constituted, respectively, 33-28% and 15-9% of the total glucose utilization rate over the range of dilution rates tested (0.038-0.064 hr-1), while the yield varied over this range from 0.066-0.085 g of biomass (dry wt) per gram of glucose.

Glucose↗

PubMed2004

High-throughput laser-mediated in situ cell purification with high purity and yield.

BACKGROUND: Technologies for purification of living cells have significantly advanced basic and applied research in many settings. Nevertheless, certain challenges remain, including the robust and efficient purification (e.g., high purity, yield, and sterility) of adherent and/or fragile cells and small cell samples, efficient cell cloning, and safe purification of biohazardous cells. In addition, existing purification methods are generally open loop and exhibit an inverse relation between cell purity and yield. METHODS: An automated closed-loop (i.e., employing feedback control) cell purification technology was developed by building upon medical laser applications and laser-based semiconductor manufacturing equipment. Laser-enabled analysis and processing has combined high-throughput in situ cell imaging with laser-mediated cell manipulation via large field-of-view optics and galvanometer steering. Laser parameters were determined for cell purification using three mechanisms (photothermal, photochemical, and photomechanical), followed by demonstration of system performance and utility. RESULTS: Photothermal purification required approximately 10(8) W/cm(2) at 523 nm in the presence of Allura Red, resulting in immediate protein coagulation and cell necrosis. Photochemical purification required approximately 10(9) W/cm(2) at 355 nm, resulting in apoptosis induction over 4 to 24 h. Photomechanical purification required more than 10(10) W/cm(2) independent of wavelength, resulting in immediate cell lysis. Each approach resulted in high efficiency purification (>99%) after a single operation, as demonstrated with eight cell types. An automated closed-loop process to re-image and irradiate remaining targets in situ was implemented, resulting in improved purification (99.5-100%) without decreasing cell yield or affecting sterility in this closed system. Efficient purification was demonstrated with B- and T-cell mixtures over a wide range of contaminating cell percentages (0.1-99%) and cell densities (10(4)-10(6)/cm(2)). Efficient cloning of 293T cells based on fluorescence with green fluorescent protein after plasmid transfection was also demonstrated. CONCLUSIONS: In situ laser-mediated purification was achieved with nonadherent and adherent cells on the automated laser-enabled analysis and processing platform. Closed-loop processing routinely enabled greater than 99.5% purity with a greater than 90% cell yield in sample sizes ranging from 10(1) to 10(8) cells. Throughput ranged from approximately 10(3) to 10(5) total cells/s for contaminating percentages ranging from 99% to 0.1%, respectively.

Automation↗

PubMed1985

Continuous-flow techniques for platelet concentrate collection: a step toward standardization and yield predictability.

This study chronicles leukocyte- and erythrocyte-depleted platelet concentrate collection by a dual stage channel in which three variables: 1) donor peripheral blood platelet concentration, 2) total blood processed, and 3) collection volume were statistically correlated with platelet yield as determined by a multiple regression analysis of single variables. Platelet concentration in the final yield was related to donor precount and collection rate, and could be varied as indicated for individual applications. Total blood processed was established by procedure time, which in turn was defined by citrate-induced calcium changes in the donor. Reduction in peripheral blood platelet concentration averaged 24% for a mean platelet yield of 3.8 X 10(11). An average of 40% of transfused platelet concentrates were recovered in recipient peripheral blood 1 hr posttransfusion and were hemostatically effective, as determined by correction of bleeding time. Platelet yields and patient response were sustained during current collection procedures, verifying the principles described during the investigative period.

Adult↗

PubMed1995

Effects of whole blood flow rates on mononuclear cell yields during peripheral blood stem cell collection using Fenwal CS 3000 Plus.

It is generally assumed that using high whole blood flow rates (WBFR), 80 ml/min, during peripheral blood stem cell (PBSC) collection on the Fenwal CS 3000 Plus blood cell processor will result in higher yields of mononuclear cells (MNC) than using lower WBFR (50 ml/min). To test this assumption, we retrospectively studied 129 PBSC procedures on 17 patients in a multiple myeloma protocol comparing MNC yield, as well as red blood cell (RBC), granulocyte, and platelet (Plt) content, of four average WBFR groups. Standard PBSC procedures were performed using modified procedure 1, interface offset 100, anticoagulant (AC) ratio of 11:1, small volume collection chamber, and a processing time of 4 hours. After correcting for AC volume used, the volume processed was divided by 240 minutes to obtain the average WBFR. WBFRs were separated into 4 groups of 40-49, 50-59, 60-69, and 70-79 ml/min. When compared to the highest flow rate group (70-79 ml/min), the three lower flow rate groups had significantly higher MNC yields of 16.2 +/- 6.9, 13.1 +/- 5.1, and 11.5 +/- 4.7 x 10(9), respectively, as compared to 8.9 +/- 6.1 x 10(9) MNC for the 70-79 ml/min group. There was no significant difference in granulocyte yield which ranged from 1.6 +/- 2.1 to 4.5 +/- 4.8 x 10(9).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

Effect of extraction method on the yield of furanocoumarins from fruits of Archangelica officinalis Hoffm.

Optimal conditions for the extraction and analysis of furanocoumarins from fruits of Archangelica officinalis Hoffm. have been determined. The following extraction methods were used: exhaustive extraction in a Soxhlet apparatus, ultrasonication at 25 and 60 degrees C, microwave-assisted solvent extraction in open and closed systems, and accelerated solvent extraction (ASE). In most cases the yields of furanocoumarins were highest using the ASE method. The effects of extracting solvent, temperature and time of extraction using this method were investigated. The highest yield of furanocoumarins by ASE was obtained with methanol at 100-130 degrees C for 10 min. The extraction yields of furanocoumarins from plant material by ultrasonication at 60 degrees C and microwave-assisted solvent extraction in an open system were comparable to the extraction yields obtained in the time- and solvent-consuming exhaustive process involving the Soxhlet apparatus.

Angelica archangelica↗

PubMed2025

Diagnostic Yield After Postnatal Reanalysis of Prenatal Exome Sequencing Results.

OBJECTIVE: Analysis of exome sequencing (ES) relies on correlation with phenotypic features, but fetal phenotyping is often incomplete. The additional yield of postnatal follow-up in cases with negative or inconclusive prenatal ES has not been demonstrated. Our objective was to assess the incremental diagnostic yield of ES reanalysis after initially negative prenatal ES for congenital anomalies incorporating features identified postnatally. METHODS: This was a secondary analysis of two prospective cohort studies of ES for fetal anomalies. We included cases in which initial ES utilizing the prenatal phenotype was not diagnostic. The primary outcome was incremental diagnostic yield of ES when incorporating postnatal findings. RESULTS: Eighty-seven cases with negative or inconclusive prenatal ES and postnatal follow-up available were included. Of those, 56 (64%) had new findings postnatally. There was an incremental yield of 2% in the entire cohort, and 7% in those with new postnatal findings. In two additional cases, postnatal evaluation suggested a specific genetic diagnosis that was not detectable with ES. CONCLUSION: Among pregnancies with fetal anomalies and no clear diagnosis identified by prenatal ES, postnatal follow-up is recommended. Reanalysis of ES results can result in a genetic diagnosis in 7% of cases with new findings.

Humans↗

PubMed2002

High yield synthesis of tentoxin, a cyclic tetrapeptide.

Tentoxin is a naturally occurring phytotoxic cyclic tetrapeptide excreted by fungi of the Alternaria alternata family. The four total syntheses of tentoxin published to date give poor total yields, mainly owing to two difficulties, the introduction of the dehydro amino acid and more especially the cyclization step. Here we describe a method that stereospecifically introduces Z-dehydrophenylalanine (deltaZPhe) by a modified Erlenmeyer aldolization reaction. The linear tetrapeptide, Boc-R1Ala-Leu-R2deltaZPhe-G1y-OMe (R1, R2: CH3, 14CH3), the precursor of tentoxin, was obtained in a 72% yield from Boc-Leu-Gly-OH. This linear tetrapeptide, labelled with carbon-14, was used for a comparative study of four cyclization reagents DPPA, DCC-PfpOH, HBTU and HATU. This last was the most effective and gave tentoxin in a 81% cyclization yield. The activated ester formed with this reagent displayed an enhanced capacity for cyclization, permitting cyclization in concentrated medium (10 mM). This new synthetic route gave tentoxin in a 60% yield from Boc-Leu-Gly-OH and offers a means of achieving the synthesis of hitherto elusive analogues.

Amino Acid Sequence↗

PubMed2026

Sparse phenotyping for wheat grain yield enabled by multiomics prediction.

Grain yield is a central target in wheat breeding, yet accurately predicting it remains challenging because it depends on many genes and responds strongly to environmental variation. Genomic selection (GS) has improved breeding efficiency by enabling genome-based prediction of genetic merit, but predictability (PA) for grain yield is often limited under stress environments. At the same time, advances in high-throughput phenotyping (HTP) using unmanned aerial vehicles (UAVs) provide phenomic data that capture environment-responsive plant performance and may complement genomic information. In this study, we evaluated genomic and phenomic models for predicting grain yield in elite bread wheat lines across irrigated, drought, and heat-stress environments. Using a sparse phenotyping framework, we compared parametric and non-parametric models. PA was evaluated within environments and under cross-environment sparse phenotyping scenarios. Genomic models provided a stable baseline and enabled effective information sharing across environments when phenotypic data were incomplete. Phenomics-only models captured environment-specific plant responses but were more sensitive to environmental context. Multiomics models that integrated genomic and phenomic information consistently achieved the highest PA, with the largest gains observed under stress conditions. Overall, our results demonstrate that integrating genomics and UAV-based phenomics within sparse phenotyping designs offers a practical and scalable approach to improve grain yield prediction in wheat.

Triticum↗

PubMed1997

Very high CO2 reduces photosynthesis, dark respiration and yield in wheat.

Although terrestrial CO2 concentrations, [CO2] are not expected to reach 1000 micromoles mol-1 for many decades, CO2 levels in closed systems such as growth chambers and glasshouses, can easily exceed this concentration. CO2 levels in life support systems in space can exceed 10000 micromoles mol-1 (1%). Here we studied the effect of six CO2 concentrations, from ambient up to 10000 micromoles mol-1, on seed yield, growth and gas exchange of two wheat cultivars (USU-Apogee and Veery-l0). Elevating [CO2] from 350 to 1000 micromoles mol-1 increased seed yield (by 33%), vegetative biomass (by 25%) and number of heads m-2 (by 34%) of wheat plants. Elevation of [CO2] from 1000 to 10000 micromoles mol-1 decreased seed yield (by 37%), harvest index (by 14%), mass per seed (by 9%) and number of seeds per head (by 29%). This very high [CO2] had a negligible, non-significant effect on vegetative biomass, number of heads m-2 and seed mass per head. A sharp decrease in seed yield, harvest index and seeds per head occurred by elevating [CO2] from 1000 to 2600 micromoles mol-1. Further elevation of [CO2] from 2600 to 10000 micromoles mol-1 caused a further but smaller decrease. The effect of CO2 on both wheat cultivars was similar for all growth parameters. Similarly there were no differences in the response to high [CO2] between wheat grown hydroponically in growth chambers under fluorescent lights and those grown in soilless media in a glasshouse under sunlight and high pressure sodium lamps. There was no correlation between high [CO2] and ethylene production by flag leaves or by wheat heads. Therefore, the reduction in seed set in wheat plants is not mediated by ethylene. The photosynthetic rate of whole wheat plants was 8% lower and dark respiration of the wheat heads 25% lower when exposed to 2600 micromoles mol-1 CO2 compared to ambient [CO2]. It is concluded that the reduction in the seed set can be mainly explained by the reduction in the dark respiration in wheat heads, when most of the respiration is functional and is needed for seed development.

Biomass↗

PubMed1997

Effect of Mixing Entropy on the Static Yield Stress of a Liquid Dispersion of Solid Particles: Comparison between Si3 N4 and Ca3 (PO4 )2 Aqueous Suspensions

Experimental measurements of the static yield stresses tau of silicon nitride (SN, Si3 N4 ) and alpha-tricalcium phosphate (TCP, alpha-Ca3 (PO4 )2 ) aqueous dispersions have been performed for different pH values of the liquid medium and, as a result, the two tau vs pH behaviors are quite different. In agreement with the DLVO theory, the static yield stress value for silicon nitride is maximal at the isoelectric point of the slurry (pHiep (SN) = 8.0 ± 0.1) and, for higher and/or lower suspension pH values, it decreases progressively. On the other hand, in tricalcium phosphate dispersed systems, the maximum value of tau is not observed at the isoelectric point (pHiep (TCP) = 6.7 ± 0.1) but two relative maximum values, taua and taub , are observed for two suspension pH values in the acid/basic environments, namely, for pH <> pHiep (TCP) . First, displacements of the pH from the isoelectric point in both environments are accompanied by an increase in tau; second, after the maximum tau values have been reached, the static yield stress decreases with the increase in the [H+ ]/[OH+ ] ions in the solution. It is shown that this phenomenon can be interpreted as an effect of the mixing entropy relative to the solid TCP aggregates, which is very sensitive to the suspension pH. Phenomenological and theoretical explanations are developed, respectively, by a heuristic recasting of the Hamaker expression for the London-van der Waals forces and by a relationship between the static yield stress and the number of solid aggregates; this relation is based on recently proposed methods for investigating the agglomeration/adsorption phenomena in a dispersed system.

Journal Article↗

PubMed1997

Spatial Distribution of Chemical Components in Aerosol Particles as Determined from Secondary Electron Yield Measurements: Implications for Mechanisms of Multicomponent Aerosol Crystallization

Secondary electron yield measurements were used to determine the distribution of chemical components in multicomponent aerosol particles formed by crystallization from aqueous solution droplets. Yield measurements were made by measuring the charge acquired by a beam of particles as they passed through an electron beam (100-600 eV energy) inside a high-vacuum apparatus. Yields were sufficiently different for certain compounds that measurements made on two-component particles could be used to obtain information on the spatial distribution of components. Variations in chemical composition as a function of depth beneath the particle surface were ascertained from the energy dependence of the measured yields, since the electron penetration depth, and therefore the probe depth, increases with electron energy. The results for mixed NaCl-NH4Cl particles indicate that the distribution of components within these particles is relatively homogeneous, while measurements made on mixed NaCl-NaNO3 particles are indicative of particles having a heterogeneous core-shell morphology. Results for mixed Na2SO4-(NH4)2SO4 particles are ambiguous, probably because of the complexity of the phase diagram of this system. It appears that the mechanism by which aerosol particles crystallize, and therefore the resulting distribution of chemical components within particles, is strongly dependent on particle composition and environmental variables. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗