Changes of Sensory Quality,Flavor-Related Metabolites and Gene Expression in Peach Fruit Treated by Controlled Atmosphere (CA) under Cold Storage

Controlled atmosphere (CA) has been used to alleviate chilling injury (CI) of horticultural crops caused by cold storage. However, the effects of CA treatment on peach fruit sensory quality and flavor-related chemicals suffering from CI remain largely unknown. Here, we stored peach fruit under CA with 5% O₂ and 10% CO₂ at 0 °C up to 28 d followed by a subsequent 3 d shelf-life at 20 °C (28S3). CA significantly reduced flesh browning and improved sensory quality at 28S3. Though total volatiles declined during extended cold storage, CA accumulated higher content of volatile esters and lactones than control at 28S3. A total of 14 volatiles were positively correlated with consumer acceptability, mainly including three C6 compounds, three esters and four lactones derived from the fatty acid lipoxygenase (LOX) pathway. Correspondingly, the expression levels of genes including PpLOX1, hyperoxide lyase PpHPL1 and alcohol acyltransferase PpAAT1 were positively correlated with the change of esters and lactones. CA elevated the sucrose content and the degree of fatty acids unsaturation under cold storage, which gave us clues to clarify the mechanism of resistance to cold stress. The results suggested that CA treatment improved sensory quality by alleviating CI of peach fruits under cold storage.     

Dynamic “operando” observation of 1 wt% Pd-based TWCs: Simultaneous XAS/DRIFTS/mass spectrometry analysis of the effects of Ce0.5Zr0.5O2 loading on structure, reactivity and performance

The behavior of 1 wt% Pd-TWCs (three-way catalysts), containing up to 33 wt% Ce_0.5Zr_0.5O₂ is followed under reducing (CO) and oxidizing (NO) cycling conditions. The dynamic behavior of these systems is analyzed using a synchronous, time-resolved energy dispersive X-ray absorption spectroscopy (XAS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectrometry (MS) set-up with subsecond time resolution. Two main physico-chemical phenomena corresponding to noble metal morphological (size/shape) changes and the redox behavior of the noble metal–promoter interface are shown to control the TWC response to NO/CO cycling conditions. Metal-only aspects strongly influence N–O dissociation and N–N coupling steps while the metal–promoter interface has a global influence on both N₂ and CO₂ formation via oxygen handling (storage/release) properties. The relative importance of these two phenomena is studied as a function of the Ce_0.5Zr_0.5O₂ promoter content of the catalysts.     

Fundamental studies of NOx storage at low temperatures

A commercial NO_x storage catalyst (Pt, BaO and alumina containing) was investigated by temperature programmed desorption (TPD) experiments in the temperature range 100–400 °C. The catalyst stored a substantial amount of NO_x at 100 °C using NO + O₂. Nitrites or loosely bound NO species are suggested for this storage, since no NO was oxidised at this low temperature. In addition, the released NO_x during the temperature ramp consisted of mainly NO and at lower temperatures the NO₂ dissociation is limited. Water and CO₂ was found to decrease the storage substantially, 92% for the NO + O₂ adsorption at 100 °C. The total storage for 60 min using NO₂ + O₂ at 200 °C was similar when introducing CO₂ and H₂O. However, the initial total uptake of NO_x was decreased. Initially we probably formed loosely bound NO_x species, which likely are strongly influenced by water and CO₂. After longer time periods are barium nitrates probably formed and they can remove the carbonates by forming stable nitrates, thus resulting in the same total uptake of NO_x.     

Effect of Empty Fruit Bunch in Calcium Oxide for Cyclic CO2 Capture

Empty fruit bunch (EFB) is utilized to increase the CO₂ capture capacity and cyclic stability of calcium oxide (CaO) prepared from cockle shells (CS). The cyclic reaction of calcination and carbonation reaction was performed in pure N₂ environment and in the presence of CO₂ in N₂, respectively. The EFB in CS modified the pore structural properties, morphology, and composition of the pristine CaO. Higher EFB loading in CS reduced the CaO composition but improved the CO₂ capture capacity and cyclic stability during cyclic CO₂ capture.     

Visualisation of mechanisms involved in Co2 injection and storage in hydrocarbon reservoirsand water-bearing aquifers

Storage of carbon dioxide (CO₂) in hydrocarbon reservoirs and saline aquifers is considered as one of the promising mitigation strategies to reduce the negative impact of this greenhouse gas. The static and dynamic behaviour of CO₂ in these storage sites which are located at various depths and geographical locations, affects the efficiency of this strategy. Understanding the impact of the conditions of these storage sites on mechanisms involved in CO₂ flow, displacement and trapping is also critical for the purpose of site selection and the design of CO₂ storage projects. In this paper we report the results of a series of CO₂ injection (CO₂I) flow visualisation (micromodel) experiments conducted using high-pressure transparent porous media representing various aquifer and depleted oil reservoirs storage conditions. The impact of pertinent parameters on the interaction between the stored CO₂ and the reservoir fluids were investigated. Both sub-critical and supercritical CO₂ were used to investigate the effect of pressure (depth) of the storage site on CO₂ trapping mechanisms. A faster CO₂ breakthrough (BT) was observed in the micromodel test simulating CO₂I into depleted oil reservoirs, compared to that into aquifers, reducing the sequestration capacity of the depleted oil reservoirs. Compared to the injection of supercritical CO₂, the BT of gaseous CO₂ happened faster, adversely affecting the CO₂ displacement performance. The results of these direct flow visualization experiments significantly improve our understanding of the complex mechanisms and interactions involved in CO₂I and storage in geological formations. This knowledge is essential for identifying storage conditions that would lead to maximising CO₂ storage capacity, for better understanding the ultimate fate of the stored CO₂ and the storage safety.     

Postharvest Treatment of Hydrogen Sulfide Delays the Softening of Chilean Strawberry Fruit by Downregulating the Expression of Key Genes Involved in Pectin Catabolism

Hydrogen sulfide (H₂S) plays several physiological roles in plants. Despite the evidence, the role of H₂S on cell wall disassembly and its implications on fleshy fruit firmness remains unknown. In this work, the effect of H₂S treatment on the shelf-life, cell wall polymers and cell wall modifying-related gene expression of Chilean strawberry (Fragaria chiloensis) fruit was tested during postharvest storage. The treatment with H₂S prolonged the shelf-life of fruit by an effect of optimal dose. Fruit treated with 0.2 mM H₂S maintained significantly higher fruit firmness than non-treated fruit, reducing its decay and tripling its shelf-life. Additionally, H₂S treatment delays pectin degradation throughout the storage period and significantly downregulated the expression of genes encoding for pectinases, such as polygalacturonase, pectate lyase, and expansin. This evidence suggests that H₂S as a gasotransmitter prolongs the post-harvest shelf-life of the fruit and prevents its fast softening rate by a downregulation of the expression of key pectinase genes, which leads to a decreased pectin degradation.     

NOx storage behavior and sulfur-resisting performance of the third-generation NSR catalysts Pt/K/TiO2–ZrO2

The NO_x storage and reduction (NSR) catalysts Pt/K/TiO₂–ZrO₂ were prepared by an impregnation method. The techniques of XRD, NH₃-TPD, CO₂-TPD, H₂-TPR and in situDRIFTS were employed to investigate their NO_x storage behavior and sulfur-resisting performance. It is revealed that the storage capacity and sulfur-resisting ability of these catalysts depend strongly on the calcination temperature of the support. The catalyst with theist support calcined at 500 °C, exhibits the largest specific surface area but the lowest storage capacity. With increasing calcination temperature, the NO_x storage capacity of the catalyst improves greatly, but the sulfur-resisting ability of the catalyst decreases. In situ DRIFTS results show that free nitrate species and bulk sulfates are the main storage and sulfation species, respectively, for all the catalysts studied. The CO₂-TPD results indicate that the decomposition performance of K₂CO₃ is largely determined by the surface property of the TiO₂–ZrO₂ support. The interaction between the surface hydroxyl of the support and K₂CO₃ promotes the decomposition of K₂CO₃ to form –OK groups bound to the support, leading to low NO_x storage capacity but high sulfur-resisting ability, while the interaction between the highly dispersed K₂CO₃ species and Lewis acid sites gives rise to high NO_x storage capacity but decreased sulfur-resisting ability. The optimal calcination temperature of TiO₂–ZrO₂ support is 650 °C.     

Influence of CO2 on storage and release of NOx on barium‐containing catalyst

A barium‐containing three‐way automotive emission catalyst was submitted to a NO_x storage step in flowing lean gas mixture containing 340 ppm NO and 8 vol% O₂ in helium. NO_x release was carried out in the 250–550°C temperature range, either in pure helium or in the presence of a 10 vol% CO₂ in helium mixture. It was shown that at 450–550°C all of the stored NO_x on the barium trap can be released fastly in the CO₂‐containing gas mixture or, after a longer time, in pure helium: these data show that NO_x release can occur in the absence of a reducing agent. The NO_x release was not complete at 350°C and did not occur at 250°C. The assisting effect of CO₂ as regards to NO_x release was interpreted in terms of the existence of the CO_2,gas + *NO_2,stored ⇌ *CO_2,stored + NO_2,gas equilibrium, suggesting the competitive storage of CO₂ and NO₂ for a unique type of barium storage sites (*). This revised version was published online in July 2006 with corrections to the Cover Date.     

<Emphasis Type="Italic">In situ</Emphasis> microobservation of the cathode in molten carbonate fuel cells

In molten carbonate fuel cells (MCFC), the wettability of the electrode and the electrolyte distribution are very important factors influencing the active reaction area. We have observed the molten carbonate behaviour directly on the cathode (porous NiO) and the electrolyte plate (LiAlO₂) under various gas conditions and at controlled potentials using an environmental scanning electron microscope (ESEM) equipped with a hot stage. We estimated the liquid electrolyte distribution in the cathode and measured the contact angles on NiO and LiAlO₂ in the electrolyte. Moreover, the electrolyte movement in the reaction CO₂ + O₂ + 2e^– = CO₃ ^2– was observed on the surface of the porous NiO in a CO₂/O₂ atmosphere. The reaction CO₃ ^2– + 2e^– = CO + 2 O^2– of the gas generation was observed in a H₂O atmosphere. The active reaction points on the electrode are the areas where the electrolyte film is thin.     

Nitrate accumulation and greenhouse gas emissions during compost storage

Greenhouse gases (CO₂, CH₄ and N₂O) are emitted during livestock manure handling, including composting, storage and land application. However, published data on emission rates of these gases during storage are sparse. In this study, the levels of GHG emissions and N levels during compost storage were investigated. The compost materials were produced by composting livestock manure for 133 d with 0, 10, 20 and 30% phosphogypsum (PG) or 10, 20 and 30% sand amendment. These compost materials were then stored on a clay pad for 233 d. Results from this study indicated that TN content did not change but mineral N content increased significantly during the 233 d storage for all treatments. The higher mineral N content in compost increases its agronomic value. There were only trace amounts of CH₄ and N₂O emissions. The C loss during storage was mainly as CO₂ and accounted for about 2.9 to 10% of total C initially in the compost. This information is vital to livestock manure life cycle analysis, and can be used to develop best manure management strategies that reduce GHG emissions from livestock production. The LRC Contribution No. 387-06006.     

NOx storage capacity,SO2 resistance and regeneration of Pt/(Ba)/CeZr model catalysts for NOx-trap system

NOx storage capacity, sulphur resistance and regeneration of 1wt%Pt/Ce_0.7Zr_0.3O₂ (Pt/CeZr) and 1wt%Pt/10wt%BaO/Ce_0.7Zr_0.3O₂ (Pt/Ba/CeZr) catalysts were studied and compared to a 1wt%Pt/10wt%BaO/Al₂O₃ (Pt/Ba/Al) model catalyst submitted to the same treatments. Pt/Ba/CeZr presents the best NOx storage capacity at 400 °C in accordance with basicity measurements by CO₂ TPD and Pt/CeZr shows the better performance at 200 °C mainly due to a low sensitivity to CO₂ at this temperature. For all samples, sulphating induces a detrimental effect on NOx storage capacity but regeneration at 550 °C under rich conditions generally leads to the total recovery of catalytic performance. However, the nearly complete sulphur elimination is only observed on Pt/CeZr. Moreover, an oxidizing treatment at 800 °C leads to partial sulphates elimination on the Pt/CeZr catalyst whereas a stabilization of sulphates on Ba containing species is observed.     

Safe storage of Co2 together with improved oil recovery by Co2-enriched water injection

The 2007 IEA's World Energy Outlook report predicts that the world's energy needs will grow by 55% between 2005 and 2030, with fossil fuels accounting for 84% of this massive projected increase in energy demand. An undesired side effect of burning fossil fuels is carbon dioxide (CO₂) emission which is now widely believed to be responsible for the problem of global warming. Various strategies are being considered for addressing the increase in demand for energy and at the same time developing technologies to make energy greener by reducing CO₂ emissions.One of these strategies is to ‘capture’ produced CO₂ instead of releasing it into the atmosphere. Capturing CO₂ and its injection in oil reservoirs can lead to improved oil recovery as well as CO₂ retention and storage in these reservoirs. The technology is referred to as CCS (carbon capture and storage). Large point sources of CO₂ (e.g., coal-fired power plants) are particularly good candidates for capturing large volumes of CO₂. However, CO₂ capture from power plants is currently very expensive. In addition to high costs of CO₂ capture, the very low pressure of the flue gas (1 atm) and its low CO₂ content (typically 10-15%) contribute to the high cost of CO₂ capture from power plants and the subsequent compression. This makes conventional CO₂ flooding (which requires very large volumes of CO₂) uneconomical in many oil reservoirs around the world which would otherwise be suitable candidates for CO₂ injection. Alternative strategies are therefore needed to utilize smaller sources of CO₂ that are usually available around oil and gas fields and can be captured at lower costs (due to their higher pressure and higher CO₂ concentration).We investigate the potential of carbonated (CO₂-enriched) water injection (CWI) as an injection strategy for improving recovery from oil reservoirs with the added benefit of safe storage of CO₂. The performance of CWI was investigated by conducting high-pressure flow visualization as well as coreflood experiments at reservoir conditions. The results show that CWI significantly improves oil recovery from water flooded porous media. A relatively large fraction of the injected CO₂ was retained (stored) in the porous medium in the form of dissolved CO₂ in water and oil. The results clearly demonstrate the huge potential of CWI as a productive way of utilizing CO₂ for improving oil recovery and safe storage of potentially large cumulative quantities of CO₂.     

Effect of fruit storage conditions on olive oil quality

"Koroneiki" olive fruit from trees grown in Crete were stored under five different conditions (0°C, air; 5°C, air; 5°C, 2% O₂+5% CO₂; 7.5°C, air; 7.5°C, 2% O₂+5% CO₂). Oil was obtained from fruit immediately after harvest and after fruit storage for 30 and 60 d. Olive oil quality was evaluated by determining acidity, peroxide value, absorption coefficients (K₂₃₂, K₂₇₀), phenol and chlorophyll content, fatty acid composition, and the resistance to oxidation by oven test. Olives stored at 7.5°C, even for 30 d, deteriorated from fungus development, and the obtained oil was of inferior quality with high acidity, peroxide value, and absorption coefficients. The same oil had high chlorophyll and phenol content, resulting in good oil resistance to oxidation. Olive oil from fruit stored at 0 or 5°C for 30 d had acceptable acidity, peroxide value, and absorption coefficients, but showed low resistance to oxidation, which was attributed to low chlorophyll and phenol content. This condition is further attributed to chilling injury caused by low storage temperatures. During storage, all treatments resulted in an increase of oleic acid, partly as a result of linoleic acid oxidation.     

“Deactivation of copper electrode” in electrochemical reduction of CO2

Metallic Cu electrode can electrochemically reduce CO₂ to CH₄, C₂H₄ and alcohols with high yields as revealed by the present authors. Many workers reported that formation of CH₄ and C₂H₄ rapidly diminishes during electrolysis of CO₂ reduction. This paper shows that such deactivation of Cu electrode is reproduced with electrolyte solutions prepared from reagents used by these workers. Deactivated Cu electrodes recovered the electrocatalytic activity for CO₂ reduction by anodic polarization at −0.05 V versus she in agreement with the previous reports. Features of the deactivation depend greatly on the individual chemical reagents. Purification of the electrolyte solution by preelectrolysis with a Pt black electrode effectively prevents the deactivation of Cu electrode. Anode stripping voltammetry of Cu electrodes, which were deactivated during electrolysis of CO₂ reduction, showed anodic oxidation peaks at ca. −0.1 or −0.56 V versus she. The severer the deactivation of the Cu electrode was, the higher electric charge of the anodic peak was observed. It is presumed that some impurity heavy metal, originally contained in the electrolyte, is deposited on the Cu electrode during the CO₂ reduction, poisoning the electrocatalytic activity. On the basis of the potential of the anodic peaks, Fe²⁺ and Zn²⁺ are assumed to be the major contaminants, which cause the deactivation of the Cu electrode. Deliberate addition of Fe²⁺ or Zn²⁺ to the electrolyte solutions purified by preelectrolysis exactly reproduced the deactivation of a Cu electrode in CO₂ reduction. The amount of the deposited Fe or Zn on the electrode was below the monolayer coverage. Electrothermal atomic absorption spectrometry (etaas) showed that Fe originally contained in the electrolyte solution is effectively removed by the preelectrolysis of the solution. Mechanistic difference is discussed between Fe and Zn in the deterioration of the electrocatalytic property of Cu electrode in the CO₂ reduction. The concentration of the impurity substances originally contained in the chemical reagents as Fe or Zn is estimated to be far below the standard of the impurity levels guaranteed by the manufacturers. Presence of trimethylamine in the electrolyte solution also severely poisons a Cu electrode in the CO₂ reduction. It was concluded that the deactivation of Cu electrode in CO₂ reduction is not caused by adsorption of the products or the intermediates produced in CO₂ reduction.     

Thermal and chemical stability of Cu–Zn–Cr-LDHs prepared by accelerated carbonation

Layered double hydroxides Cu_xZn_6 − xCr₂(OH)₁₆(CO₃)·4H₂O with different molar ratios of Cu/Zn/Cr were synthesized by accelerated carbonation. The products were characterized by XRD, SEM, FT-IR and TG-DTG-DSC-MS. The chemical stability was tested by the modified Toxicity Characteristic Leaching Procedure (TCLP). The results showed that the products were the mixture of Cu_xZn_6 − xCr₂(OH)₁₆(CO₃)·4H₂O and (CuZn)₂(CO₃)(OH)₂, with similar thermal behavior. All products were chemically stable with reduced leaching at pH > 6 (Cu²⁺, Zn²⁺) or > 5 (Cr³⁺).     

CO2 pressure effects on melting, crystallization, and morphology of poly(vinylidene fluoride)

Supercritical CO₂ fluids (SCF CO₂) assisting melting of poly(vinylidene fluoride) (PVDF) and the SCF CO₂ pressure affecting surface and bulk morphology, melting and crystallization of PVDF were investigated by means of SEM, AFM, FTIR, WAXD, DSC and SAXS. Three SCF CO₂ conditions at 84, 283, and 476 atm all at 140 °C for 30 min were studied. Morphological changes, induced by melting of PVDF under SCF CO₂ and recrystallization during depressurization of CO₂, were found. The level of the CO₂-assisted melting of PVDF was found to increase with increasing pressure. SEM and AFM images showed that the 84 atm of CO₂ assisted melting on the surface of PVDF film while both 283 and 476 atm of CO₂ gave rise to melting of the whole film. FTIR spectra and WAXD patterns found that the hot-pressed PVDF film exhibited predominant α-crystalline form, which is one of the reported four crystalline forms including α, β, γ, and δ forms, and did not transform to other crystalline form(s) upon the SCF CO₂ treatments although they lowered the bulk crystallinities of PVDF. SEM images showed that the SCF CO₂ treatments at 283 and 476 atm resulted in foam formations in PVDF, with smaller foam cells resulting from the lower pressure treatment. SAXS data found that the thickness of crystalline layer in the lamellar stacks increased while that of amorphous layers insignificantly changed after SCF CO₂ treatments at 283 and 476 atm, as compared with untreated PVDF. SAXS and DSC data suggested the presence of a bimodal distribution of crystal size of PVDF after SCF CO₂ treatments.