Volumetric Growth Rate Research Articles

Small Renal Masses Initially Managed Using Active Surveillance: Results From a Retrospective Study With Long-Term Follow-Up

BackgroundThe purpose of this study was to provide outcomes of patients managed using active surveillance (AS) for small renal masses (SRMs). Patients and MethodsWe retrospectively reviewed data of 62 patients diagnosed with 64 contrast enhancing SRMs suspicious for renal cell carcinoma. We evaluated the differences between patients who remained on AS and those who underwent delayed surgical intervention. ResultsThe mean age of patients was 75 years and the mean follow-up was 91.5 months. The median tumor size and the median estimated tumor volume were 2.6 cm and 8.7 cm3, respectively. The median linear growth rate and the median volumetric growth rate were 0.7 cm/y and 8.8 cm3/y, respectively. The mean linear and volumetric growth rates of the group of patients who underwent surgery was higher than in those who remained on surveillance (1.9 vs. 0.4 cm/y and 16.1 vs. 4.6 cm3/y, respectively; P < .001). ConclusionMost SRMs show an indolent course, with low metastatic potential. Faster linear and volumetric growth rates could be the expression of malignant disease, thus suggesting the need for a delayed surgical intervention. AS is a reasonable option for the management of SRMs in properly selected patients with low life expectancy.

Vigilancia activa de masas renales pequeñas diagnosticadas en pacientes de edad avanzada o con comorbilidad: en busca de la mejor estrategia de tratamiento

IntroductionAim of this study is to provide our results after long-term active surveillance (AS) protocol for small renal masses (SRMs), and to report the outcomes of patients who remained in AS compared to those who underwent delayed surgical intervention. Patients and methodsWe retrospectively reviewed our database of 58 patients diagnosed with 60 contrast enhancing SRMs suspicious for renal cell carcinoma (RCC). All patients had clinical and radiological follow-up every 6 months. We evaluated the differences between patients who remained on AS and those who underwent surgical delayed intervention. ResultsThe mean age was 75 years, the mean follow-up was 88.5 months. The median initial tumor size at presentation was 2.6cm, and the median estimated tumor volume was 8.7cm3. The median linear growth rate of the cohort was 0.7cm/year, and the median volumetric growth rate was 8.8 cm3/year. Death for metastatic disease occurred in 2 patients (3.4%). No correlation was found between initial tumor size and size growth rate. The mean linear and volumetric growth rates of the group of patients who underwent surgery was higher than in those who remained on surveillance (1.9 vs. 0.4cm/year and 16.1 vs. 4.6 cm3/year, respectively; P<.001). ConclusionsMost of SRMs demonstrate to have an indolent course and low metastatic potential. Malignant disease could have faster linear and volumetric growth rates, thus suggesting the need for a delayed surgical intervention. In properly selected patients with low life-expectancy, AS could be a reasonable option in the management of SRMs.

Application of sodium- and biogenic sulfide to the precipitation of nickel in a continuous reactor

Attention has been focused in recent decades upon the precipitation of metal sulfides from acid mine drainage (AMD) and pregnant leach solutions, due to the advantages of the sulfide precipitation process over traditional methods employing hydroxides. The aim of this work was thus to explore technologies for the precipitation of valuable metals, such as nickel using such sulfides (as either Na2S or biogenic sulfide). The recovery of nickel sulfide was improved when the initial pH of the solution containing each metal was set to 7. In such a condition the removal efficiency of nickel was 99.9%, corresponding to a residual level of 0.13mgL−1 for nickel in solution. Kinetic parameters for precipitation were determined from the particle size distributions (produced in an MSMPR reactor) using the method of moments, where the growth and nucleation rates, as well the agglomeration kernel, were calculated. The precipitation of nickel at an initial pH of 7 showed a nucleation rate value of 8.16×1018#m−3s−1, the highest volumetric growth rate (1.03×101μm−3s−1) and agglomeration kernel of 9.71×10−23m3#−1s−1. The biogenic sulfide was a suitable alternative to sodium sulfide for nickel removal. Both sodium sulfide and biogenic sulfide can be utilized to precipitate nickel as millerite (NiS), allowing the effluent compliant with environmental legislation.

Volumetric tumor growth in advanced non‐small cell lung cancer patients with EGFR mutations during EGFR‐tyrosine kinase inhibitor therapy

BACKGROUNDThe objective of this study was to define the volumetric tumor growth rate in patients who had advanced nonsmall cell lung cancer (NSCLC) with sensitizing epidermal growth factor receptor (EGFR) mutations and had initially received treatment with EGFR‐tyrosine kinase inhibitor (TKI) therapy beyond progression.METHODSThe study included 58 patients with advanced NSCLC who had sensitizing EGFR mutations treated with first‐line gefitinib or erlotinib, had baseline computed tomography (CT) scans available that revealed a measurable lung lesion, had at least 2 follow‐up CT scans during TKI therapy, and had experienced volumetric tumor growth. The tumor volume (in mm3) of the dominant lung lesion was measured on baseline and follow‐up CT scans during therapy. In total, 405 volume measurements were analyzed in a linear mixed‐effects model, fitting time as a random effect, to define the growth rate of the logarithm of tumor volume (logeV).RESULTSA linear mixed‐effects model was fitted to predict the growth of logeV, adjusting for time in months from baseline. LogeV was estimated as a function of time in months among patients whose tumors started growing after the nadir: logeV = 0.12*time + 7.68. In this formula, the regression coefficient for time, 0.12/month, represents the growth rate of logeV (standard error, 0.015/month; P &lt; .001). When adjusted for baseline volume, logeV0, the growth rate was also 0.12/month (standard error, 0.015/month; P &lt; .001; logeV = 0.12*months + 0.72 logeV0 + 0.61).CONCLUSIONSTumor volume models defined volumetric tumor growth after the nadir in patients with EGFR‐mutant, advanced NSCLC who were receiving TKI, providing a reference value for the tumor growth rate in patients who progress after the nadir on TKI therapy. The results can be studied further in additional cohorts to develop practical criteria to help identify patients who are slowly progressing and can safely remain on EGFR‐TKIs. Cancer 2013;119:3761–3768. © 2013 American Cancer Society.

Conditional sampling of transitional boundary layers in pressure gradients

AbstractStatistical analysis of transitional boundary layers in pressure gradients is performed using the flow fields from direct numerical simulations of bypass transition. Laminar–turbulent discrimination separates the streaky laminar flow from turbulent regions. Individual streaks are identified and tracked in the flow field in order to obtain statistics of the amplitude of the streak population. An extreme value model is proposed for the distribution of streak amplitudes. It is also possible to differentiate those streaks which break down into turbulent spots from innocuous events. It is shown that turbulence onset is due to high-amplitude streaks, with streamwise perturbation velocity exceeding 20 % of the free stream speed. The resulting turbulent spots are tracked downstream. The current analysis allows for the measurement of the lateral spreading angles of individual spots and their spatial extent and volumes. It is demonstrated that the volumetric growth rate of turbulent spots is insensitive to pressure gradient.

Assessment of volumetric growth rates of small colorectal polyps with CT colonography: a longitudinal study of natural history

The clinical relevance and in-vivo growth rates of small (6-9 mm) colorectal polyps are not well established. We aimed to assess the behaviour of such polyps with CT colonography assessments. In this longitudinal study, we enrolled asymptomatic adults undergoing routine colorectal cancer screening with CT colonography at two medical centres in the USA. Experienced investigators (PJP, DHK, JLH) measured volumes and maximum linear sizes of polyps in vivo with CT colonography scans at baseline and surveillance follow-up. We defined progression, stability, and regression on the basis of a 20% volumetric change per year from baseline (20% or more growth classed as progression, 20% growth to -20% reduction classed as stable, and -20% or more reduction classed as regression). We compared findings with histological subgroups confirmed after colonoscopy when indicated. This study is registered with ClinicalTrials.gov, number NCT00204867. Between April, 2004, and June, 2012, we screened 22,006 asymptomatic adults and included 243 adults (mean age 57·4 years [SD 7·1] and median age 56 years [IQR 52-61]; 106 [37%] women), with 306 small colorectal polyps. The mean surveillance interval was 2·3 years (SD 1·4; range 1-7 years; median 2·0 years [IQR 1·1-2·3]). 68 (22%) of 306 polyps progressed, 153 (50%) were stable, and 85 (28%) regressed, including an apparent resolution in 32 (10%) polyps. We established immediate histology in 131 lesions on colonoscopy after final CT colonography. 21 (91%) of 23 proven advanced adenomas progressed, compared with 31 (37%) of 84 proven non-advanced adenomas, and 15 (8%) of 198 other lesions (p<0·0001). The odds ratio for a growing polyp at CT colonography surveillance to become an advanced adenoma was 15·6 (95% CI 7·6-31·7) compared with 6-9 mm polyps detected and removed at initial CT colonography screening (without surveillance). Mean polyp volume change was a 77% increase per year for 23 proven advanced adenomas and a 16% increase per year for 84 proven non-advanced adenomas, but a 13% decrease per year for all proven non-neoplastic or unresected polyps (p<0·0001). An absolute polyp volume of more than 180 mm(3) at surveillance CT colonography identified proven advanced neoplasia (including one delayed cancer) with a sensitivity of 92% (22 of 24 polyps), specificity of 94% (266 of 282 polyps), positive-predictive value of 58% (22 of 38 polyps), and negative-predictive value of 99% (266 of 268 polyps). Only 16 (6%) of the 6-9 mm polyps exceeded 10 mm at follow-up. Volumetric growth assessment of small colorectal polyps could be a useful biomarker for determination of clinical importance. Advanced adenomas show more rapid growth than non-advanced adenomas, whereas most other small polyps remain stable or regress. Our findings might allow for less invasive surveillance strategies, reserving polypectomy for lesions that show substantial growth. Further research is needed to provide more information regarding the ultimate fate of unresected small polyps without significant growth. US National Institutes of Health, National Cancer Institute.

Lights and shadows: growth patterns in three sympatric and congeneric sponges (Ircinia spp.) with contrasting abundances of photosymbionts

The life-history traits of long-lived benthic littoral invertebrates remain poorly understood. In this study, we analysed patterns of growth in three abundant sublittoral sponges from the western Mediterranean Sea, chosen for their close phylogenetic relatedness, sympatric distribution, and contrasting amounts of photosymbionts: high in Ircinia fasciculata, lower in I. variabilis, and absent in I. oros. Sponge area, perimeter, number of oscula, and epibiont abundance were quantified from in situ digital images taken monthly for 1.5 years and volumetric growth rates were calculated from empirical area–volume relationships. Volumetric growth rates were different among species and coherent with the photosymbiont abundance: high in I. fasciculata (40.03 ± 4.81 % year−1, mean ± SE), low in I. variabilis (5.65 ± 6.11 % year−1), and almost nil in I. oros (−0.04 ± 3.02 % year−1). Furthermore, a marked seasonality was observed in the first two species, with greater growth during the warm season. The high growth rates of I. fasciculata were likely fuelled by symbiont-derived photosynthates and required to compete in the well-lit, algal-dominated habitats this species prefers. In contrast, I. variabilis and I. oros tended to dwell in shaded habitats, where competition from slow-growing invertebrates is intense, and featured lower growth rates. The flattened morphology and lower circularity of I. variabilis indicates a capacity for adaptation to any space that is freed, while I. oros had less oscula and was more massive and circular, suggesting a strategy of passive occupation and minimisation of biological interactions. The results show that even congeneric species living sympatrically can achieve important biomass using different growth and substrate occupation strategies.

Volumetric tumor growth in advanced NSCLC patients (pts) with EGFR mutations during EGFR-TKI therapy: Developing criteria to define slow progression.

e19125 Background: EGFR-mutated advanced NSCLC pts treated with EGFR TKI typically progress after an initial tumor response. Most pts continue TKI beyond RECIST progression, and an objective guide for treatment decisions is needed. We analyzed the volumetric tumor growth in these pts as an initial step to develop criteria for slow progression to aid therapeutic decision making. Methods: The study population included 58 advanced NSCLC pts with sensitizing EGFR mutations, treated with first-line single-agent gefitinib or erlotinib between 2002-2011, who had baseline CT showing measurable lung lesion and at least two follow-up CTs while on TKI and experienced volumetric tumor growth. Tumor volume (mm3) of the dominant lung lesion was measured on baseline and all follow-up chest CT scans during therapy, using volume analysis software [Nishino et al. Acad Radiol. 2011]. A total of 405 volume measurements from nadir to the end of TKI therapy or last follow-up, with data closure on 6/1/12, were analyzed in a linear mixed effects model, fitting time as a random effect [Laird and Ware, Biometrics, 1982]. Results: Among 58 pts, 46 (79%) were female, median age was 62 (range: 35-84), 29 (50%) were never-smokers, 53 (91%) were stage IV at diagnosis, and 53 (91%) received erlotinib. The median time on TKI was 15.8 months. The median time to tumor nadir was 6.3 months. A linear mixed effects model was fitted to predict growth of the logarithm of tumor volume (logeV), adjusting for time in months from baseline. The growth rate of logeV, obtained as the regression coefficient for time, was 0.12/month (SE: 0.015; p&lt;0.001; logeV=0.12*months+7.68). The model provided a reference value for the volumetric tumor growth rate in EGFR-mutant NSCLC pts after they have achieved their nadir. Conclusions: Tumor volume analysis defined volumetric tumor growth after the nadir in EGFR-mutant advanced NSCLC pts receiving TKI. This provides a reference value for the tumor growth rate in pts progressing after the nadir on TKI. Based on these data which can be studied in additional cohorts, we are currently developing practical radiographic criteria to help define patients as slow progressors who can safely remain on EGFR TKIs.

Tungsten-based pillar deposition by helium ion microscope and beam-induced substrate damage

The authors use a helium ion microscope (HIM) equipped with a tungsten hexacarbonyl gas injection system (GIS) to form tungsten-based pillars on carbon and silicon substrates by helium ion beam-induced deposition. Tungsten-based pillars with a width of ∼40 nm and height of ∼2 μm (aspect ratio of ∼50) are successfully fabricated using the HIM-GIS method. The pillars consist of face-centered cubic WC1−x and/or W2(C, O) grains. Columnar voids with a width of 1–15 nm form in the center of the pillars, suggesting that the pillars are continuously sputter-etched by the incident helium ion beam during deposition. In addition, the authors observe beam irradiation damage in the form of blistering of the Si substrate at the interface between the pillar and Si substrate. The columnar void width and Si blister height decreases as the volumetric growth rate of the pillars increases regardless of the deposition parameters. The authors consider that at least three phenomena compete during pillar formation, namely pillar deposition, sputter-etching, and Si blistering. Although there are numerous parameters involved in HIM-GIS deposition, it appears that the volumetric growth rate determines both the microstructure of the tungsten-based pillars and the degree of substrate damage.

Surveillance for small renal masses: retrospective analysis of a cohort of 42 patients with long-term follow-up

To provide our experience with active surveillance in patients incidentally diagnosed with small renal masses and show the results of long-term follow-up. We retrospectively evaluated a cohort of 42 patients diagnosed with small renal mass (≤ 4 cm in diameter). All patients had clinical and radiological follow-up every 6 months. We evaluated the differences between patients who remained on surveillance and those who underwent surgical delayed intervention and the correlations between clinical variables and size growth rate. The mean patients' age was 75 years (66-90); the mean follow-up was 69.4 months (range 35-168). The median initial tumor size at presentation was 2.5 cm (range 1-4.3), and the median estimated tumor volume was 8.6 cm(3) (range 1.7-42.3). The median growth rate of the cohort was 0.8 cm/year (range 0.2-2.9), and the median volumetric growth rate was 9.1 cm(3)/year (range 0-19.6). Death for metastatic disease occurred in 2 patients died due to metastatic disease (4.7 %). No correlation was found between initial tumor size and size growth rate. The mean growth rate of the group of patients who underwent surgery was higher than in those who remained on surveillance (1.8 vs. 0.4 cm/year; P < 0.001). The most of small renal masses initially managed by surveillance will grow slowly and will have a low metastatic potential. Tumor size at diagnosis is not able to predict the natural history of renal masses, even if malignant disease may have a higher growth rate. In elderly patients with relevant co-morbidities, surveillance can be a reasonable option alternative to surgery.

Biomass accumulation in a biofilter treating toluene at high loads – Part 2: Model development, calibration and validation

In this work, a dynamic model describing volatile organic compounds abatement and the corresponding biomass accumulation is developed, calibrated and validated. The mathematical model is based on detailed mass balances which include the main processes involved in the system: advection, absorption, adsorption, diffusion, biodegradation and biomass growth. The model overcomes common assumptions considered in classical biofiltration models such as uniform, constant biomass distribution. The model was calibrated and validated using experimental data obtained from a biofilter packed with clay pellets during its operation from inoculation to clogging. The model was able to predict satisfactorily experimental data by calibrating only a minimum number of parameters such as the half-saturation constant for toluene and the volumetric maximum growth rate of microorganisms. Kinetic parameters were fitted by means of an optimization routine using toluene concentration profiles along the bed height of the biofilter. A confidence interval for each parameter was calculated based on the Fisher Information Matrix procedure. The model was satisfactorily validated during the operation of the biofilter under different process conditions. Biomass accumulation permitted to predict macroscopic, critical operating parameters such as the pressure drop through the bed. The model may help predicting energy consumption requirements as well as biomass clogging episodes due to excessive biomass growth.

Bevacizumab for Progressive Vestibular Schwannoma in Neurofibromatosis Type 2

Early studies suggest that bevacizumab treatment can result in tumor shrinkage and hearing improvement for some patients with neurofibromatosis type 2 (NF2). The aim of this study was to report extended follow-up in a larger cohort of similarly treated patients. Retrospective study. Tertiary referral center Thirty-one consecutive NF2 patients who received bevacizumab for progressive vestibular schwannomas. Hearing improvement, defined as an improvement in word recognition score above the 95% critical difference compared with baseline, and radiographic response, defined as a 20% or greater decrease in tumor volume compared with baseline. The median age was 26 years (range, 12-73 yr). The median volumetric tumor growth rate before treatment was 64% per year. At the time of analysis, the median duration of treatment was 14 months (range, 6-41 mo) with a total of 47 patient-years of follow-up. A hearing response occurred in 57% (13/23) of evaluable patients and a radiographic response in 55% (17/31) of target vestibular schwannomas. The median time to response was 3 months for both end points. The only clinical or radiographic feature at baseline that correlated with change in tumor volume at 3 months was the mean apparent diffusion coefficient value, a radiologic marker of edema (p = 0.036). Ninety percent of patients had stable or improved hearing after 1 year of treatment and 61% at 3 years; 88% of patients had stable or decreased tumor size after 1 year of treatment and 54% at 3 years. Overall, treatment was well tolerated. Bevacizumab treatment was followed by hearing improvement and tumor shrinkage in more than 50% of progressive vestibular schwannomas in NF2 patients. Stable or improved hearing was retained in the majority of patients.

Natural growth and disease progression of non-small cell lung cancer evaluated with 18F-fluorodeoxyglucose PET/CT

PurposeThe aims of this study were to: (1) estimate the volumetric and metabolic growth rate of non-small cell lung cancer (NSCLC), (2) evaluate disease progression prior to treatment, and (3) explore the effects of tumor growth rate and time to treatment (TTT) on survival outcome. MethodsPatients with inoperable stages I–III NSCLC with serial pre-treatment PET/CT scans were eligible for this study. PET-derived metabolic tumor volumes (PET-MTV) and CT-derived gross tumor volumes (CT-GTV) were contoured using PET/CT information. Normalized standardized uptake values (NSUV) in tumors including the NSUVmean and NSUVmax were measured. Tumor growth rates expressed as doubling time (DT) were estimated using an exponential model. Pre-treatment disease progression defined as the development of any new site of disease on PET/CT and change in TNM stage (AJCC 7th ed.) were recorded. Growth rate and tumor progression were analyzed with respect to overall (OS) and progression free survival (PFS). ResultsThirty-four patients with a median inter-scan interval (ISI) of 43 days and TTT of 48 days were analyzed. Tumor volumes showed remarkable inter-scan growth while NSUV did not increase significantly. The DT for PET-MTV, CT-GTV, NSUVmean and NSUVmax were 124, 139, 597, and 333 days, respectively. Pre-treatment disease progression occurred in 20.6% patients with longer ISI being a significant risk factor (OR=1.027, p=0.02). The optimal threshold ISI to predict progression was 58 days (4.8% vs. 46.2%, p=0.007). Neither tumor growth rates nor TTT were significantly correlated to OS or PFS. ConclusionsNSCLC displays rapid tumor volume growth whereas NSUVmean and NSUVmax are relatively stable over the same time period. Longer delays before initiation of treatment are associated with higher risk of pre-treatment disease progression.

Adaptation of a flocculent Saccharomyces cerevisiae strain to lignocellulosic inhibitors by cell recycle batch fermentation

The ethanol production from lignocellulosic feedstocks is considered a promising strategy to increase global production of biofuels without impacting food supplies. However, some compounds released during the hydrolysis of lignocellulosic materials are toxic for the microbial metabolism, causing low ethanol yield and productivity during the fermentation. As an attempt to overcome this problem, the present study evaluated the adaptation of a flocculent strain of Saccharomyces cerevisiae (NRRL Y-265) to several inhibitory compounds usually found in lignocellulosic hydrolysates (acetic acid, furfural, hydroxymethylfurfural, vanillin, syringaldehyde, and hydroxybenzoic acid), aiming to minimize their negative effects on yeast metabolism, maximizing the ethanol production as a consequence. Cell recycle batch fermentation (CRBF) was performed during 39 consecutive days, using five different fermentation media with sequential increase in the concentration of inhibitory compounds, simulating the composition of lignocellulosic hydrolysates. This strategy allowed obtaining a yeast strain with increased ethanol volumetric productivity and growth rate (10% and 70% respectively, over parent strain) able to produce ethanol with better results when cultivated in glucose-supplemented steam-exploded eucalyptus hydrolysate.

Long-term follow-up of 287 meningiomas in neurofibromatosis type 2 patients: clinical, radiological, and molecular features

Decision-making criteria for optimal management of meningiomas in neurofibromatosis type 2 (NF2) patients is hampered by lack of robust data, particularly long-term natural history. Seventy-four NF2 patients harboring 287 cranial meningiomas followed up for a mean period of 110.2 months were studied retrospectively. The median number of meningiomas per patient was 3. The mean maximum diameter of meningiomas at diagnosis was 14.3 mm, with a mean annual growth rate of 1.5 mm. Sixty-six percent of tumors showed no or minimal growth. In a subgroup of patients with 3D MRI, 7.3% of meningiomas (28% of patients) had a volumetric growth rate 20% or more per year. Twenty-five de novo meningiomas appeared during the follow-up (8.7%) and demonstrated a higher growth rate than other meningiomas (6.6 mm/year). Fifty-six meningiomas (23%) in 34 NF2 patients (45.9%) were operated on during the follow-up period. Among symptomatic resected meningiomas, grades II and III tumors were found in 29% and 6% of cases, respectively, with a remarkable intratumor histological heterogeneity. Single nucleotide polymorphism array analysis of 22 meningioma samples in 14 NF2 patients showed increasing chromosome instability with increasing grade, the most frequent losses being on 22q, 1p, 18q, and 6p. This study provides clues to improve tailored treatment of meningiomas: de novo and brain edema-associated meningiomas require active treatment. Future clinical trials in NF2 need to focus specifically on meningiomas as the primary endpoint and should include patients with meningiomas growing 20% or more per year in order to assess new treatments.

Special Solutions to the Ortega Equation

The previously established augmented growth equation (Cosgrove, Plant Physiol 78:347–356, 1985; Ortega, Plant Physiol 79:318–320, 1985), suitable for description of pressure relationships in the growing plant cell, is revised with respect to the inclusion of changing cell wall properties hitherto represented by two constants, Φ and e, connected with viscoelastic behavior. This phenomenological equation in the modified form is capable of appropriate description of volumetric extensibility, growth rate, and pressure changes in growing plant cells. This concerns deposition of new material in the polymer cell wall intercalation process, but it can also be used successfully for induced cell wall loosening, for example, by expansin EXPA (EXPB) proteins. In this context, a specific shape of the proposed equations, armed with a small number of physiologically explained parameters, opens up an experimental perspective for determining vital numbers connected with interactions at the nanoscale (polymer bonds “dilution” of an extending cell wall), or even at the molecular level in the cell wall (calculating numbers proportional to the expansin molecule’s active surface area). A systematic survey of ready-to-use deterministic solutions originating from the Ortega equation, reporting on both reversible (elastic) and irreversible (plastic) features of a growing plant cell, is presented. These findings also provide a quantitative cytomechanical model able to account for the important role of mechanical properties of the cell wall in cellular growth processes. An important feature of the analytical approach is that all model equations, after calibrating on existing data, allow new results to be inferred without further experimental work.

Nannochloropsis production metrics in a scalable outdoor photobioreactor for commercial applications

Commercial production of renewable energy feedstocks from microalgae will require reliable and scalable growth systems. Two and one half years of biomass and lipid productivity data were obtained with an industrial-scale outdoor photobioreactor operated in Fort Collins, Colorado (USA). The annualized volumetric growth rates for Nannochloropsis oculata (CCMP 525) and Nannochloropsis salina (CCMP 1776) were 0.16gL−1d−1 (peak=0.37gL−1d−1) and 0.15gL−1d−1 (peak=0.37gL−1d−1) respectively. The collective average lipid production was 10.7m3ha−1yr−1 with a peak value of 36.3m3ha−1yr−1. Results from this study are unique based on publication of biomass and corresponding lipid content combined with demonstration of energy savings realized through analysis of gas delivery requirements, water recycling from successive harvests with no effect on productivity, and culture stability through serial batch lineage data and chemotaxonomic analysis of fatty acid contents.

Continuous growth facilitates feeding and reproduction: impact of size on energy allocation patterns for organisms with indeterminate growth

Body size has great influence on feeding, reproduction, and ecological importance. This study measures growth, reproduction, and feeding for several northeastern Pacific intertidal invertebrates that have indeterminate growth. In all species studied, linear size (length, diameter) showed asymptotic growth fit by the von Bertalanffy growth function, supporting the notion that less energy is allocated to growth with age because of increased reproduction. However, these same species displayed a continuous, roughly linear increase in volume with age. Both reproductive output and food intake were shown to scale proportionally with volume. This indicates that some species with indeterminate growth do not reduce energy allocation to growth with age but instead display continuous volumetric growth that facilitates increases in feeding rate and reproductive output with age and size. A simple allometric model is proposed to describe constant volumetric growth rates and linear increases in reproduction with age.

Different influences of nucleating agents on crystallization behavior of polyethylene and polypropylene

The crystallization behavior of polyethylene (PE) and polypropylene (PP), including the neat ones and the ones nucleated with the same nucleating agent (NA), was studied by DSC. It was found that the nucleating agent decelerated the PE nonisothermal crystallization process. NA did enhance the nucleating rates for both PE and PP, but the linear growth rate dominated the volumetric growth rate for PE, and the volumetric growth rate dominated the overall crystallization rate. That is why PE nucleated with NA had a slower overall crystallization rate than the neat one.

3-D phase-field simulation of grain growth: Topological analysis versus mean-field approximations

The characteristics of 3-D grain growth are investigated by a topological analysis of phase-field simulation results compared with theoretical mean-field theories. We found that the size distribution of the grains starting from an arbitrary narrow distribution crosses the self-similar Hillert distribution, and ends in a distribution with relatively longer tails of large grains in which the central peak shifted towards smaller grain size. The distribution of topological classes, as characterized by the number of facets per grain, is found to be time-invariant for the process as a whole. The obtained shape function is in good agreement with the analytical distribution function derived based on the average N-hedron model [Rios PR, Glicksman ME. Act Mater 2008;56:1165]. The volumetric growth rate per topological class also correlates well with the analytical approach obtained by Mullins [Mullins WW. Acta Mater 1956;3:900]. The relationship between grain size and its shape, however, deviates from theoretical predictions.