Heptane Concentration Research Articles

Integrated interferometers as a new platform for low cost gas chromatography detection

Gas chromatography is a reference method for gas analysis. As part of efforts to miniaturize gas chromatography systems, the miniaturization of detectors is essential. In this work, we report a new integrated photonic platform for gas chromatography analyte detection. The fabricated silicon die integrates Mach-Zehnder interferometers into low dead volume microfluidic channels, with coherent cost-effective detection scheme with a fixed 850 nm wavelength laser. A proof of concept is demonstrated with the separation and detection of three volatile organic compounds: heptane, octane, and toluene. Peaks’ widths at half height range from 1 to 5 s. Peaks are very well resolved by our system, which acquires more than 100 points per second. From a heptane dilution range, we evaluate the limit of detection of our system to be the headspace of a 0.26 % heptane concentration solution. To our knowledge, these are the first integrated Mach-Zehnder interferometers reported for gas chromatography detection. This work could open new strategies for fast low cost and low limit of detection specific gas chromatography silicon micro-detectors.

Effect of asphaltene flocculation size on deposition using a modified quartz crystal microbalance in-house setup and microscopic image analysis: Model oil, inhibitory and nanoparticle solutions case studies

Asphaltene deposition phenomenon is a challenging event that may occur during the oil production process, causing difficulties such as formation damage and wettability alteration. To overcome these challenges, inhibitors and nanoparticles are commonly used as treatments. The size of asphaltene flocculation is a critical factor in the deposition process. In this study, we investigated the effect of asphaltene flocculation size on deposition using the quartz crystal microbalance (QCM) method in both model oil and inhibitory solutions containing Linear alkylbenzene (LABs), Sodium laureth sulfate (SLES), and 4-Dodecylbenzenesulfonic (DBSA), as well as solutions with nanoparticles such as TiO2 and SiO2. A novel in-house setup was designed to overcome experimental challenges and microscopic images were used as a visual approach for better interpretation of results. Our findings showed that TiO2 and SLES had the greatest performance in postponing flocculation points among nanoparticles and inhibitory solutions, respectively. We also observed that inhibitors were more effective in delaying the flocculation point as the concentration of heptane in the model oil decreased, with a weakened effect at higher heptane concentrations. Based on the interaction of forces, we obtained an average surface area of 17.5 square micrometres as the required value for aggregate deposition. Furthermore, inhibitory solutions showed a much lower growth rate and smaller aggregates compared to normal solutions.

Exploring the Connection between the Occurrence and Intensity of "Grubby" Defect and Volatile Composition of Olive Oil.

In order to investigate the relationship between the occurrence of the "grubby" sensory defect caused by olive fruit fly (Bactrocera oleae (Rossi)) infestation and the resulting volatile composition, virgin olive oils were extracted from olives of the Leccino cultivar with 0%, 50%, and 100% olive fly infestations and subjected to analysis of the basic chemical quality parameters, fatty acids and volatiles, and sensory analysis by the Panel test. A 100% olive fly infestation reduced the basic chemical quality of the oil, while the fatty acid composition was not affected in any case. The overall sensory quality score and intensity of the positive sensory attributes decreased, while the intensity of the "grubby" defect increased proportionally to the degree of infestation. The occurrence and intensity of this defect were clearly causally related to the concentrations of 3-methylbutanal, 2-methylbutanal, β-ocimene, ethyl 2-methylbutyrate, dimethyl sulfoxide, 4-methyl-5H-furan-2-one, α-farnesene, 6-methyl-5-hepten-2-one, 1-octanol, E-2-nonen-1-ol, benzeneacetaldehyde, heptanal, and octanal, implying that the perception of "grubby" comes from their joint contribution to the overall olive oil flavour. In addition to contributing to the understanding of the chemical origin of "grubby", the results obtained could potentially be used to develop strategies to support sensory analysis in the classification of olive oil quality and the confirmation of the presence of this sensory defect in oil samples.

Quantification of p-Cymene and Heptane in a Solvent-Based Green Process of Polystyrene Recycling

The development of an economically viable technology for recycling polystyrene (PS) is of crucial importance. Most postconsumer PS feedstocks cannot be handled by mechanical recycling due to severe contamination. A solvent-based process was developed by Polystyvert and uses p-cymene as a solvent to solubilize PS and heptane as an antisolvent to precipitate it. This leads to the production of recycled PS resin of high purity. However, the optimization of this process requires the knowledge of p-cymene, heptane, and PS concentrations at different stages, where the samples of interest can be a viscoelastic paste or a solid (pellets). Here, we present an infrared spectroscopy (IR) method that can rapidly quantify the content of these samples at the plant level. Partial least squares statistical modeling on the first derivative IR spectra allowed the simultaneous quantification of the components with a limit of quantification of 0.5% and 1% for p-cymene and heptane. To illustrate the usefulness of this method, samples from a pilot PS-recycling plant were tested to improve the washing efficiency of the process.

Synthesis of Tetracosane Functionalized Titanium Dioxide Sensor for Detecting Heptane as Pneumonia Breath Biomarker

Pneumonia is a significant worldwide health burden, resulting in more than 2.5 million deaths in 2017. The technology able to screen for pneumonia in an effortless, rapid, and at point-of-care manner is needed today in healthcare settings. Monitoring changes in volatile organic compounds in patient breath during sickness has been considered as one of the possible disease screening methods for many years. In this work, coated nanostructured titanium dioxide sensors are used for gaseous amperometric detection of heptane, a volatile organic compound associated with pneumonia. Tetracosane coated sensors showed an increase in current when exposed to heptane at a biased voltage of 1.5V under ambient room temperature. Different heptane concentrations are shown to be directly related to sensors’ response. As the concentrations of heptane in gaseous samples increased, the sensors’ response increased. Additionally, tetracosane sensors were shown to be reusable and have 30 days of shelf life at room temperature.

Features of the long-term dynamics of heart rate variability among workers of a potash ore processing enterprise

Introduction. Currently, the violation of heart rate variability as one of the main pathogenetic mechanisms of the damaging effect of pollutants, associated effects on the cardiovascular system. The study aims to explore the dynamics of the influence of the autonomic nervous system (ANS) on heart rate variability (HRV) in workers of a potassium ore processing enterprise exposed to industrial pollutants (fine fractions of potassium chloride dust, formaldehyde, hexane, heptane) with an assessment of changes in dependence from work experience, establishment of cause-and-effect relationships of violations of heart rate variability with exposure to chemical compounds. Materials and methods. The object of the study was 140 employees of a potash ore processing enterprise, assigned to the observation group, and 76 employees of the administrative and technical apparatus, who made up the comparison group. Samples were taken from the air of the working medium for the content of saturated hydrocarbons (hexane, heptane), the vapors of formhehyde were considered, and the presence of fine particles PM2.5 and PM10 was established. Investigation of biological media (blood, urine) of workers at the enterprise determination of formaldehyde in blood, hexane and heptane in urine. Evaluation of heart rate variability was carried out on a computer electrocardiograph "Poli-Spectr-8/EX" using a cardiorhythmographic program using the method of time analysis, variation pulsometry and spectral analysis. Results. The concentration of fine particles in the air at the workplaces of the observation group was 12-111 times higher for PM2.5, and 5.6-74.6 times higher for PM10 than for the work places of the comparison group. The concentration of formaldehyde, hexane and heptane in the air did not exceed hygienic standards. In the observation group relative to the comparison group, formaldehyde blood was 1.5 times (p<0.001), in the urine of hexane - 1.2 times (p=0.011), heptane - 1.3 times (p=0.046). It was found that with an experience of up to 10 years, formaldehyde in the blood of workers in the observation group was 1.4 times higher than that in the comparison group (p=0.011), with an experience of more than 10 years - 1.7 times (p=0.005). In the urine of workers in the observation group with work experience of up to 10 years, an excess of 1.3 (p=0.026) relative to the comparison group of hexane was found. HRV data analysis. With damage to the length of service in the observation group, there was a significant decrease in the temporal analysis indicators (SDNN, ms, RMSSD, ms, pNN50, %, CV, %), while in the comparison group, only the CV, % decrease was statistically significant; the values of IN conventional units, AMo, % significantly increased (p=0.03 and p=0.003, respectively). A statistically significant relationship was established between the likelihood of an increase depending on the content of heptane in urine (b0=0.22; b1=10.6; F=21.5; R2=0.09; p=0.0001) and formaldehyde in the blood (b0=0.02; b1=6.55; F=69.6; R2=0.25; p=0.0001) in the surveyed workers. Conclusions. Activation of central ergotropic and humoral-metabolic mechanisms, a tendency towards a decrease in parasympathetic influences. The method of logistic regression analysis established a statistically significant relationship between the probability of an increase in the stress index depending on the heptane content in the blood of the surveyed suppliers.

Changes in biochemical parameters in workers exposed to chemical production factors (heptane and hexane)

Introduction. Long-term constant exposure to certain representatives of aliphatic hydrocarbons during the extraction and processing of potash ore can lead to pathological changes on critical organs and systems in production workers. The study aims to evaluate the change in biochemical parameters in workers exposed to chemical production factors (heptane and hexane). Materials and methods. The study of the content of hexane, heptane in the air of the working area and the urine of workers, the establishment of changes in several biochemical (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, glutamyltransferase, epinephrine, and norepinephrine) and general clinical (eosinophils, neutrophils and the eosinophilia index) indicators, modeling of cause-and-effect relationships. Results. Specialists found in the observation group relative to the comparison group: increased levels of heptane and hexane in the urine up to 1.7 times; increased levels of adrenaline and norepinephrine in the blood plasma up to 1.8 times, up to 1.4 times ALAT and γ-GT in the blood serum, up to 1.9 times neutrophils in the nasal secretions associated with increased concentrations of heptane and hexane in the urine; an increase of up to 4.4 times in the frequency of diseases of the nervous system, respiratory organs, and digestion. Conclusions. In the air of the working area of the workers of the flotation shop of the sylvinite processing plant, the concentrations of the studied limit hydrocarbons were below the detection limit; there is an increased concentration of heptane and hexane in the urine. In the workers of the studied production, an increase of 1.4-1.8 times in the level of adrenaline and norepinephrine in blood plasma, 1.2-1.4 times in ALAT and γ-GT in blood serum, 1.9 times in the content of neutrophils in nasal secretions, which characterizes adverse effects from the respiratory, digestive and nervous systems. We proved the dependence of the increased frequency of diseases of the listed organs and systems on the increased concentration of heptane in the urine (R2=0.26-0.43; p=0.0001-0.028).

Indoor air quality in shopping and storage areas.

In retail stores, workers are constantly exposed to new manufactured goods. The issue of the exposure of retail workers to volatile organic compounds (VOCs) should clearly be considered. Therefore, this study provides data regarding VOC concentrations in ten French retail stores. The stores were chosen to represent various products: sports goods, shoes and leather, furniture, car equipment, bazaars, online-sales storage, clothes, books, DIY (do-it-yourself), and household appliances. VOCs and aldehydes were actively sampled on the same day in five to seven locations per building and outdoors. Toluene and formaldehyde were omnipresent with indoor concentrations reaching 252 and 53µg/m3 , respectively. The car equipment store, followed by clothing, shoes, and leather, and DIY stores showed the worst indoor air quality. High concentrations were measured, for example, the maximum α-pinene concentration in the furniture and DIY stores was 364 and 141µg/m3 , respectively, and the heptane concentration in the car equipment store reached 1,316µg/m3 . Two VOCs classified as toxic to reproduction were measured: hexane in the car equipment store and the bazaar, and dimethylformamide in the sports goods store. This study shows some disparities in the indoor concentrations among different locations in the same store, particularly between sales and storage areas.

Analysis of Combustion Process of Protective Coating Paints

Structural elements in buildings exposed to high temperature may lose their original stability. Application of steel structures has several advantages; however, deflection under exposure to high temperatures may be a potential obstacle. Therefore, the aim of the study was to determine how temperature affects decomposition of protective paints applied in the construction. A dedicated installation for the analysis of the combustion process of protective coating paints in a laboratory scale was prepared. The experimental device consisted of the following parts: top-loading furnace connected to the gas conditioner, the LAT MG-2 gas mixer, and portable gas analyzer GASMET DX-4010. The following type of the protective powder coating paints were analyzed: alkyd and polyurethane. The obtained results indicated that during thermal decomposition of paints, formaldehyde, benzene, heptane, and butanol were released, however in different concentrations. Moreover, decomposition temperature affected the type and amount of released gas mixture components. With increasing temperature, increased release of formaldehyde and benzene was noticed, while the concentration of butanol and heptane decreased. Finally, the product of thermal decomposition emitted in the highest concentration was formaldehyde, which can cause irritation and sensitization in humans.

Combustion of heptane-in-water emulsion foamed with hydrogen-oxygen mixture

One of the perspective types of combined fuels is the oil-in-water emulsion foamed with the hydrogen-oxygen mixture. In this paper, the process of combustion of such a system obtained via hydrogen-oxygen mixture bubbling through the heptane-in-water emulsion is considered experimentally for the first time. The main goal of this paper is to study different regimes of foamed emulsion combustion at varying composition of hydrogen-oxygen mixture inside bubbles and heptane content in the emulsion. Flame speed is measured with the use of high-speed filming. It is shown that the use of hydrogen allows increasing the speed of flame propagation through the foamed emulsion, and at certain conditions even detonation onset becomes possible. The detonation in the foamed emulsion is determined by the effect of energy focusing during the collapse of gaseous bubbles. When using a lean hydrogen-oxygen mixture, the dependence of the total burning rate of the foamed emulsion on heptane concentration has a maximum. It is found that when using the stoichiometric hydrogen-oxygen mixture, the flame speed decreases monotonically with the increase in heptane concentration. In the case of a weakly reactive compound of the foamed emulsion, the regime of spinning detonation is possible.

Effects of asphaltene concentration and asphaltene agglomeration on viscosity

Asphalenes are regarded as the most polar and heaviest components in crude oil system. Their precipitation and agglomeration cause problems in oil recovery, production, and transportation. Asphaltenes are directly responsible for determining the viscosity of crude oil. In this work, the effects of asphaltene concentration and asphaltene agglomeration on viscosity were investigated. Toluene and heptane were used as asphaltene solvent and precipitant. The viscosities of asphaltenes-toluene solutions with various asphaltene concentrations were measured to investigate the impact of asphaltene concentration on viscosity. The results indicate that the viscosity of asphaltene-toluene solution exponentially increases with the asphaltene concentration. Elevated temperature causes viscosity reduction. The effect of temperature on viscosity reduction is more significant at higher asphaltene concentration. The dependence of viscosity on temperature can be well described by the Arrhenius equation, by considering the significance of activation energy. On the other hand, the asphaltene agglomerates form and grow with the increase of heptane concentration in crude oil-heptane-toluene mixture. A sharp viscosity rise of crude oil-heptane-toluene mixture was observed beyond heptane threshold concentration of 60 vol%. This is mainly resulted from the significant formation and growth of asphaltene agglomerates in asphaltene suspensions. The interactions between micro-sized asphaltene agglomerate particles could significantly affect the viscosity of liquid–solid system. The particle properties of asphaltene agglomerates including size, size distribution, number and shape factor were analyzed by microscopic images of the synthetic diluted oil. These contribute to the understanding of the effect of particle properties of asphaltene agglomerates on the viscosity of oil suspension.

Off-flavor caused by cold storage is related to induced activity of LOX and HPL in young coconut fruit

Off-flavor after cold storage is the major consumer complaint relating to consumption of young coconut fruit. To understand its chemical basis, young coconut fruit were stored for up to 4 weeks at either 4 or 25 °C, followed by volatile analysis. Off-flavor was detected at 4 °C in both water and kernel tissue after one week of storage and then increased quickly thereafter. PatternHunter analysis showed that volatiles from the lipid oxidation pathway, heptanal, octanal, nonanal and heptanol, were positively correlated with the development of fruit off-flavor during cold storage. Lipoxygenase (LOX) and hydroperoxide lyase (HPL) were related to the formation of lipid-derived volatiles and activities of both of these enzymes were high in fruit during cold storage. Fruit wrapped with polyethylene (PE) film reduced LOX and HPL activities, reduced the concentrations of heptanal, octanal, nonanal and heptanol and inhibited off-flavor development relative to fruit wrapped with polyvinyl chloride (PVC) film.

Procedure LIAM (LDAR, IR Camera, Analyzing & Modeling) to determine the contribution of ambient emissions and combustion of hydrocarbon

In special petroleum areas where the petrochemical, petroleum and gas industries are located, ambient emissions are the first and most environmental pollutants that are undetectable. The present study aims to assess the environmental pollutants resulting from leaks and fixed resources of Olefin unit in the Arya Sasol Petrochemical Complex located in Asaluyeh, south of Iran. In this study, the LIAM method (LDAR, IR Camera, Analyzing & Modeling) was for sampling process during four seasons from 2016 to 2017. Leak points of the unit were detected by IR Camera and LDAR program. AERMODE software was also used to model the dispersion of SO2, NOX, CO2 and particulate matters released from the fixed resources. In the next, IDW method in ArcGIS 10.2 was conducted to interpolate the environmental pollutants. The interpolation of the annual average of pollutants showed that the concentration of benzene, butadiene, ethylbenzene, heptane and SO2 in some sections is higher than the environmental standards. The results of AERMODE modeling showed that the maximum 24-h concentration and annual average of SO2 only in autumn have exceeded the clean air standard. The combination of proposed methods in this study can be used as a smart way to evaluate the industrial pollutants.

Formation of the oxidized flavor compounds at different heat treatment and changes in the oxidation stability of milk.

The oxidized flavor could affect the sensory acceptability of consumers. In this study, the oxidized flavor compound (OFC) in different heated milk was analyzed using the solid phase microextraction–gas chromatography–mass spectrometry (SPME–GC–MS). The concentration of OFC increased with increasing the intensity of heat treatment. The concentrations of heptanal, nonanal, 2‐heptanone, and 2‐nonanone in the heated milk samples were in the range of 1.88–5.51, 1.03–3.26, 6.89–88.04, and 1.46–12.78 μg/kg, respectively. The correlation coefficients between the OFC and the heat intensity were above 0.86. It was found that the intensity of heat treatment (below 80°C for 10 min) could not cause the significant changes in the distribution of fat globules. The contents of partial proteins in milk fat globule membrane gradually destructed with increasing the intensity of heat treatment. The DPPH˙ scavenging activity reduced by 23.15%, and the peroxide value (POV) increased by 37.23% as raw milk was heated at 90°C for 20 min. Values of thiobarbituric acid reactive substances (TBARS) had a tendency to increase as the heated time was operated for 20 min (p < 0.05). It indicated the heat treatment could change the oxidative environment of milk and influence the distribution of milk fat and the formation of oxidized flavor compounds.

Solvatochromic and nonlinear optical properties of Eosin B in solvents and AOT/water/Heptane

The third-order susceptibility and second-order hyperpolarizability and the two-photon absorption coefficient of Eosin-B in AOT/water/Heptane were investigated by using the Z-Scan technique. The droplets were prepared with an AOT/water droplet in a continuous phase of Heptane. The droplets size changes with the amount of water and the droplet concentration decreases with the increase of Heptane concentration. To study the nonlinear optical properties of Eosin-B, the Z-scan measurements were performed by means of a laser at 532 nm and 80 mW power. The nonlinear refractive and the nonlinear absorption coefficient indices were found to be in the order of 10−12 (cm2 W−1) and 10−7 (cm W−1), respectively. The change of nonlinear optical properties of Eosin-B by droplet size and concentration is due to the change of dye aggregation and thermal conductivity and thermo-optic coefficient of samples. The absorption of Eosin-B changes with the polarity of the medium (dielectric constant and refractive index). It has been shown that the intensity of emission spectra of Eosin-B in AOT/water/Heptane is enhanced compared to that of aqueous solution. By the Bilot and Kawski theory, the ratio between the excited state and the ground state of the dipole moments (μe/μg) of Eosin-B both in water and in droplets is extracted.

Impact of black soldier fly larvae meal on the chemical and nutritional characteristics of rainbow trout fillets

The present research studied the effect of a dietary inclusion with Hermetia illucens larvae meal (Hi) on rainbow trout’s fillets chemical composition. The effect of Hi inclusion in diets on rainbow trout chemical characteristics was evaluated. Trout were fed three different diets: control (C, no Hi inclusion), 25% and 50% of substitution of fish meal with Hi (Hi25 and Hi50, respectively). Fillets were analysed to quantify proximate composition, carbohydrates percentage, colour parameters, nucleotides concentration, fatty acids profile, volatile organic compounds (VOCs) and myofibrillar and sarcoplasmic concentrations. Diets did not affect proximate composition. Contrariwise, Hi50 diet decreased fillet yellowness and both substitution percentages affected negatively adenosine monophosphate concentration. Saturated fatty acids, mostly C12 : 0, increased their contents in relation with Hi inclusion at the expense of monounsaturated and polyunsaturated (both n-3 and n-6) fatty acids. Less modifications were reported in VOCs as only heptanal and octanal concentrations were affected, no new compounds appeared in relation with Hi inclusion. No modifications in proteins patterns were shown even if myofibrillar content decreased in trout fed Hi50. The results highlighted that chemical modifications occurred in fillets were related to the chemical composition of the H. illucens meal and to the percentage of inclusion in the diet. Substitution of fish meal with a precisely percentage of H. illucens meal could be a potential future solution in order to decrease the quantity of fish meal used in aquafeeds.

Exhaled volatile substances mirror clinical conditions in pediatric chronic kidney disease.

Monitoring metabolic adaptation to chronic kidney disease (CKD) early in the time course of the disease is challenging. As a non-invasive technique, analysis of exhaled breath profiles is especially attractive in children. Up to now, no reports on breath profiles in this patient cohort are available. 116 pediatric subjects suffering from mild-to-moderate CKD (n = 48) or having a functional renal transplant KTx (n = 8) and healthy controls (n = 60) matched for age and sex were investigated. Non-invasive quantitative analysis of exhaled breath profiles by means of a highly sensitive online mass spectrometric technique (PTR-ToF) was used. CKD stage, the underlying renal disease (HUS; glomerular diseases; abnormalities of kidney and urinary tract or polycystic kidney disease) and the presence of a functional renal transplant were considered as classifiers. Exhaled volatile organic compound (VOC) patterns differed between CKD/ KTx patients and healthy children. Amounts of ammonia, ethanol, isoprene, pentanal and heptanal were higher in patients compared to healthy controls (556, 146, 70.5, 9.3, and 5.4 ppbV vs. 284, 82.4, 49.6, 5.30, and 2.78 ppbV). Methylamine concentrations were lower in the patient group (6.5 vs 10.1 ppbV). These concentration differences were most pronounced in HUS and kidney transplanted patients. When patients were grouped with respect to degree of renal failure these differences could still be detected. Ammonia accumulated already in CKD stage 1, whereas alterations of isoprene (linked to cholesterol metabolism), pentanal and heptanal (linked to oxidative stress) concentrations were detectable in the breath of patients with CKD stage 2 to 4. Only weak associations between serum creatinine and exhaled VOCs were noted. Non-invasive breath testing may help to understand basic mechanisms and metabolic adaptation accompanying progression of CKD. Our results support the current notion that metabolic adaptation occurs early during the time course of CKD.

Tailored Alloying Extent and Structural Evolution of Mesostructured PtRu Nanoparticles on Microemulsion Lyotropic Liquid-Crystalline Phases with Varied Heptane Concentrations

We investigated the structural evolution, atomic distribution, and alloying extent of mesostructured PtRu nanoparticles electrochemically reduced on microemulsion lyotropic liquid-crystalline (MLLC) templates on addition of heptane at varied concentrations using in situ small-angle X-ray scattering and in situ X-ray diffraction, complemented with X-ray absorption spectra and a transmission electron microscope. The structural stability of the MLLC template with heptane added is much improved compared to that of the corresponding LLC without alkane. For the duration of electrochemical reduction, a structural transition occurred from hexagonal to lamellar phase of MLLC templates when the heptane concentration was more than 8 wt %. With increasing heptane concentration, atomic distribution, and alloying extent, the CO tolerance factor of PtRu nanoparticles were considerably improved. The mesostructured PtRu nanoparticles produced on MLLC-directed templates with heptane at a concentration of 8 wt % show a stru...

Volatile organic compounds in watermelon (Citrullus lanatus) grafted onto 21 local and two commercial bottle gourd (Lagenaria siceraria) rootstocks

SummaryVolatile organic compounds (VOCs) are responsible for flavour development in watermelon (Citrullus lanatus). The objective of this study was to investigate the rootstock effects of 21 local bottle gourd [Lagenaria siceraria (Molina) Standl.] accessions collected from the Mediterranean region (Turkey) on the concentrations of VOCs in watermelon over 2 years. The watermelon cultivar ‘Crimson Tide’ was used as the scion and two commercial bottle gourd rootstocks were also used for comparison. The VOCs in each rootstock-scion combination were analysed using static headspace (SHS) and gas chromatography-mass spectrometry (GC-MS). A total of 24 VOCs were identified in watermelon fruit, including 11 aldehydes, seven alcohols, four ketones, one heterocyclic compound, and one acid. Acetaldehyde (25.9 – 39.5% of the total peak areas), propanal (5.0 – 8.3%), 2-propanone (2.5 – 4.9%), pentanal (2.1 – 3.6%), hexenal (14.5 – 22.6%), (E)-2-hexenal (0.4 – 2.3%), 6-methyl-5-hepten-2-one (10.0 – 19.05%), nonanal (1.6 – 4.4%), (Z)-6-nonenal (4.0 – 9.8%), (E)-2-nonenal (0.6 – 2.0%), (E,Z)-2,6-nonadienal (2.1 – 3.7%), (Z)-6-nonenol (1.0 – 3.2%), and (E,Z)-3,6-nonadienol (1.0 – 3.7%) were the most abundant VOCs found in all watermelon scions. There was no significant effect (P ≥ 0.05) of rootstock on the concentrations of acetaldehyde, propanal, pentanal, heptanal, ethanol, 1-pentanol, 2-propanone, 2-pentyl furan, or acetic acid. Propanal, 2-propanone, and acetic acid were identified as VOCs in watermelon for the first time. Hexanal, (Z)-6-nonanal, and 6-methyl-5-hepten-2-one concentrations were strongly affected by rootstock. The results showed that the local bottle gourd accessions 07-06 and 31-09, in particular, were the most promising genotypes in terms of producing favourable VOCs. Except for the local bottle gourd accessions 33-35, 01-17, and 07-04, the other 18 gourds accessions had high potential as rootstocks for breeding programmes in watermelon with regard to desirable VOC concentrations. Rootstock 31-09 should be considered for commercial production in terms of improved disease resistance, fruit yield, and fruit quality.

Tuning the Shape of Mesoporous Silica Particles by Alterations in Parameter Space: From Rods to Platelets

The knowledge of how to control the pore size and morphology of separated mesoporous silica particles is crucial for optimizing their performance in applications, such as molecular sieves and drug delivery systems. In this work, we have systematically studied the effects of various synthesis parameters to gain a deeper understanding of how particle morphologies can be altered. It was found that the morphology for isolated particles of SBA-15 type, with unusually short and wide pores, could be altered from rods to platelets by variations in the NH4F concentration. The pore length is nearly constant (~300 nm) for the different morphologies, but the particle width is increasing from 200 nm to >3 μm when decreasing the amount of NH4F, and the pore size can be tuned between 10 and 13 nm. Furthermore, other synthesis parameters such as heptane concentration, pH, silica precursor, and additions of ions have also been studied. The trend regarding particle width is independent of heptane concentration, at the same time as heptane increases the particle length up to a plateau value of ~500 nm. In all, parameters controlling particle width, length, and pore size have been separated in order to evaluate their function in the particle formation. Additionally, it was found that the formation time of the particles is strongly affected by the fluoride ion concentration, and a mechanism for particle formation for this system, where micelles transform from a foam, to multilamellar vesicles, and finally to cylindrical micelles, is suggested.