Dipping Solution Research Articles

Evaluation of test strips for the rapid identification of ethylenediaminetetraacetic acid (EDTA) specimens.

Identification of specimens that contain ethylenediaminetetraacetic acid (EDTA) is frequently necessary when investigating potentially mislabeled or improperly collected specimens. To evaluate the performance of rapid EDTA detection test strips in clinical specimens. We applied specimens to test strips designed to detect EDTA (QUANTOFIX EDTA) using a pipet (drop mode). Reactions were scored visually on a scale from red (no EDTA) to orange (low/indeterminate EDTA) to yellow (contains EDTA). Test strips reliably identified specimens from EDTA-containing tube types. Although test strips did not detect strong reactivity in other specimens, tubes containing NaFl/K-oxalate produced an orange (low/indeterminate EDTA) reaction. Bismuth and citrate levels were higher in specimens after we dipped test strips into solution (dip mode). Test strips detected the presence of EDTA in concentrations found in EDTA-containing primary tubes. Test strips were less effective in evaluating low-level EDTA concentrations expected with intravenous line contamination or backflow. Indeterminate reactions required further investigation. Dip mode can produce analytical problems for assays that measure (or are interfered by) the contents of test strips.

Investigation of Acetic Acid Corrosion Impact on Printed Solar Cell Contacts

In this paper, the corrosion mechanism behind damp heat-induced degradation of screen-printed silver front-side contacts of silicon solar cells due to the presence of acetic acid, which is known to be a decomposition product of the most common module encapsulation material ethylene vinyl acetate, is investigated. Scanning electron microscope (SEM) investigations and solder and peel-tests show that the interaction between screen-printed contacts and acetic acid results in a significant adhesion loss of the front-side metallization due to the corrosion of the glass layer inside the contacts. The application of a reductive potential to the front contact accelerates this process considerably and enables it at lower acetic acid concentrations. The analysis of the dissolved corrosion products of the contact (lead, silver) by chemical trace analysis (inductively coupled plasma optical emission spectrometry) and the generation of Pourbaix diagrams of lead in acetic acid enable the elaboration of a detailed model, which suggests a cycle of dissolution and subsequent reduction of the dissolved species as the mechanism behind the corrosion of the contacts in the model experiment and most probably in module application. Cyclic voltammetry measurements with acetic acid dipping solutions support this conclusion.

(Invited) Self-Assembly on Graphene and 2D Materials

Nanostructured monolayers of molecules can be formed at a variety of interfaces. At a liquid-solid interface, such two-dimensional (2D) molecular assemblies can be created by depositing a solution of the compound of interest on top of the substrate (drop casting) or by immersing the substrate into a solution (dip coating). Very often, only weak non-covalent interactions govern the interplay between molecules and molecules and substrate. Advanced interface specific methods such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM) provide structural and other types of information at the nanoscopic level. In this presentation, we focus on several aspects of molecular self-assembly at the interface between a liquid or air, and substrates such as highly oriented pyrolytic graphite and graphene. Highly oriented pyrolytic graphite can be considered as an excellent model surface for adsorption and self-assembly of molecules on graphene. We will discuss the concept of 2D crystal engineering and the effect of solvent, solute concentration and temperature, bringing insight into thermodynamic and kinetics aspects of the self-assembly process at the interface between a liquid and graphite or graphene.1,2 Based on these insights, we will demonstrate molecular self-assembly based functionalization of graphite and graphene.3 Various applications will be presented,4 including tunable doping of graphene based field effect transistors5. (1) De Feyter, S.; De Schryver, F. C. Chem.Soc.Rev. 2003, 32, 139. (2) Mali, K. S.; Adisoejoso, J.; Ghijsens, E.; De Cat, I.; De Feyter, S. Acc.Chem.Res. 2012, 45, 1309. (3) Li, B.; Tahara, K.; Adisoejoso, J.; Vanderlinden, W.; Mali, K. S.; De Gendt, S.; Tobe, Y.; De Feyter, S. ACS Nano 2014, 7, 10764. (4) Xu, H.; Saletra, W. J.; Iavicoli, P.; Van Averbeke, B.; Schenning, A. P. H. J.; Beljonne, D.; Lazzaroni, R.; Amabilino, D. B.; De Feyter, S. Angew. Chem. Int. Ed. 2012, 51, 11981. (5) Li, B.; Klekachev, A.; Cantoro, M.; Huyghebaert, C.; Stesmans, A.; Asselberghs, I.; De Gendt, S.; De Feyter, S. Nanoscale 2013, 5, 9640. Figure 1

Unraveling the Effect of PbI2 Concentration on Charge Recombination Kinetics in Perovskite Solar Cells

CH3NH3PbI3 perovskite solar cells have rapidly risen to the forefront of emerging photovoltaic technologies. A solution-based, two-step method was reported to enhance the reproducibility of these solar cells. In this method, first a coating of PbI2 is applied by spin-coating onto a TiO2-coated substrate, followed by a dip in a methylammonium iodide solution, leading to conversion to CH3NH3PbI3. The concentration of PbI2 in the spin-coating solution is a very important factor that affects the infiltration of the perovskite and the amount deposited. The best solar cell performance of 13.9% was obtained by devices prepared using 1.0 M of PbI2 in dimethylformamide. These devices also had the longest electron lifetime and shortest carrier transport time, yielding lowest recombination losses. Rapid quenching of the perovskite emission is found in device-like structures, suggesting reasonably good efficient carrier extraction at the TiO2 interface and quantitative extraction at the spiro–OMeTAD interface.

Effect of Processing Parameters on the Stability of Nonpasteurized Mango Slice Preserves

Process factors influencing the production of nonpasteurized mango slice preserves were studied. The initial dipping conditions, the composition of the storage syrup and the use of Citrus aurantifolia essential oil (CEO) as a preservative were taken into account. The results obtained by applying the response surface methodology permitted us to propose the combination of dipping time, citric acid and sugar percentages of the storage solution, which provided a 99% stability probability of the nonpasteurized preserves for 4 weeks. This achievement was further ameliorated by modifying the storage solution and including CEO. The best process factors increased the shelf life up to 6 months with associated dipping in a hot solution at 55C with storage solution composed of 2% citric acid, 1% ascorbic acid, 1% calcium chloride, 17.4% sugar and 1,000 ppm CEO. The adopted mild process factors could be a good strategy for nonthermal processed fruit products. Practical Applications Production of preserves is a technology widely used for the transformation of fruits. Pasteurization, which is a key unit in most of the current processes applied, is one of the reasons of consumer's rejection of the product in terms of organoleptic acceptance. The results of this work contributes to the understanding of factors affecting the stable production of mango preserves without pasteurization and gives indications on the replacement of synthetic preservatives with the use of Citrus aurantifolia essential oil while maintaining the shelf life of the product up to 6 months.

Effect of Decontamination Processing on the Removal of Chlorpyrifos and Cypermethrin Residues from Tomato Fruits

Laboratory experiments were carried out to evaluate the effect of different tomato fruit decontamination processing like washing, cooking, washing plus cooking and dipping in chemical solutions on reduction of chlorpyrifos and cypermethrin residues after application of ready-mix formulation Cannon 55EC (chlorpyrifos 50% +cypermethrin 5%) on the crop. Ready-mix formulation Cannon 55EC was applied twice at the rate of 1ml/L at 15 days interval. Tomato fruits were collected at 0 (2 hours) and 3 days interval after the last spray and subjected to decontamination processes. Washing of zero day contaminated fruit samples provided 40.04–71.07% relief from chlorpyrifos residues and 42.10–73.19% relief from cypermethrin residues. Cooking degraded chlorpyrifos residues up to 48.82–62.23% and cypermethrin residues by 62.17–67.10%. Washing plus cooking was found to be the best technique in removing the residues. Washing of fruits in solutions like NaOH (2%) and HCl (0.05%) has also shown good relief from chlorpyrifos and cypermethrin residues.

Effect of Organic Acids Pretreatments on Physicochemical Properties and Shelf Life of Refrigerated Bolti Fish : Tilapia Nilotica

Quality of whole Nile Bolti fish (Tilapia nilotica) stored under refrigeration at 4±1°C after dipping in aqueous solutions (2 liter of dipping solution: 1 kg of fish) of acetic acid (AA, 1%), citric acid (CA, 3%) and mixture of (1% AA+ 3% CA) for 5 minutes was investigated. Changes in physicochemical parameters (chemical composition, pH, thiobarbituric acid values (TBA), total volatile basic nitrogen contents (TVB-N), water holding capacity (WHC) and plasticity) were evaluated during 12 days of storage. The data revealed that, the suggested treatments were significantly affected the chemical composition, especially for the lipids and protein contents. Sample dipped in acetic acid (1%) had significantly lower pH value (5.95), at the end of storage time than the control and other treated samples. The highest values of WHC during storage were given by fish samples treated with CA followed by AA and its combination with CA. Significant reduction in TBA concentrations and total TVB-N in fish samples treated with selected organic acids was assessed when compared to control. In conclusion, the results found that acetic acid and citric acid solutions, especially in combinations, can be utilized as safe organic preservatives for Boltifish under refrigerated storage up to 12 days. Keywords:Bolti fish, acetic acid, citric acid, refrigerated storage, physicochemical properties

Effect of Addition of Surfactant to the Surface Hydrophilicity and Photocatalytic Activity of Immobilized Nano-TiO<sub>2</sub> Thin Films

We study the effect of adding cetrimonium bromide (CTAB) as a surfactant to titanium dioxide (TiO2) solution for immobilizing TiO2 on glass substrates. The thin films are deposited by the dip-coating technique. After dipping into the TiO2 sol, the films are calcined and a pure anatase crystal phase is obtained. The thickness of the thin film is changed by varying the number of the dip-and-calcine cycles. The prepared films are characterized using FE-SEM, TG-DTA, and XRD, and samples’ photocatalytic performances are tested with regard to the degradation of methylene blue dye. Aside from the photocatalytic performance, the photoinduced hydrophilicity of thin TiO2 films surface is also studied.Characterization results show that the addition of surfactant gives rise to characteristic patterns on the surface of the TiO2 thin film, which also affects the photocatalytic activity. The addition of CTAB to the TiO2 dipping solution has a negative effect because the calcination temperature is not sufficiently high to burn all the surfactants off. As for surface wettability, the addition of surfactant has a positive effect on the photoinduced surface hydrophilicity of the TiO2 films under UV light.

What else can we do to mitigate contamination of fresh produce by foodborne pathogens?

What else can we do to mitigate contamination of fresh produce by foodborne pathogens?

Effects of Chitosan or Calcium Chloride on External Postharvest Qualities and Shelf-Life of ‘Holland’ Papaya Fruit

Papaya ( Carica papaya L.) is an important fruit widely cultivated commercially throughout Thailand. Its all year around fruit bearing capability makes papaya a popular fruit with Thai people. Unfortunately, papaya has a very limited shelf-life, as such; the objective of this research was to delay the external postharvest qualities by using chitosan and calcium chloride on the ‘Holland’ variety of papaya fruit. The experiment was arranged in a Factorial Completely Randomized Design, composed of two factors: coating with chitosan at four concentrations (1.0, 1.5, 2.0 or 2.5%) or dipping in calcium chloride solution at four levels (1.0, 1.5, 2.0, or 2.5%), compared with control fruits. After treating, all treatments were stored under ambient temperature (27 °C, 80% R.H.). The results showed that fruit treated with chitosan, irrespective of any concentrations, had the least similar fruit weight loss after six days of storage; however, fruit-treated with 2.5% chitosan showed the maximum fruit firmness and a delayed red color appearance on the fruit skin. In addition, the best treatment for extending shelf-life proved to be from a treatment of 2.5% chitosan.

Technological Solutions to Increase Shelf Life of Fresh Meat Burger

The present study examined the combined effect of dipping in sodium lactate solutions, as antimicrobial preservative, cochineal mixture, as natural color improver and modified atmosphere packaging (MAP) on meat burger shelf life. The work was divided into two subsequent experimental steps, the first one was aimed to select the optimal concentration of combined additives, whereas the last trial was aimed to test the best combination with MAP (MAP1, 30% O2 70% CO2 and MAP2, 70% O2 30% CO2). The shelf life was determined by the microbiological and sensory quality decay kinetics. Results indicated that the meat burger's shelf life could be extended using the two additives alone or combined with MAP2 until approximately 8 and 10 days, respectively. Practical Applications Meat burger is a very popular food commodity around the world and its consumption has increased over the last decades in many countries. Considering the fact that meat burger belongs to perishable foods, the main concern of industries is their shelf life extension. The results presented in this work indicate that the combination of sodium lactate and cochineal mixture with modified atmosphere packaging can satisfy this particular need and prolong the shelf life of meat burger. Considering that the proposed strategy is simple and relatively inexpensive, it could be very beneficial and of commercial importance to the meat industry.

Food Preferences of Workers of Coptotermes formosanus (Isoptera: Rhinotermitidae)

Coptotermes formosanus Shiraki is an amphibious termite which severely damages wood components of housing construction, stored cellulose materials, living trees, and communication facilities. The food preference of this termite was investigated in laboratory conditions. Our research results indicated that among 8 kinds of woods (teak Tectona grandis, Chinese fir Cunninghamia lanceolata, oak Quercus mongolica, taxis Melia azedarach, birch Betula allegansis, beech Fagus syliatica, pine Pinus massoniana, and poplar Populus tremula), the consumption rate of pine wood by C. formosanus (30.46%) is higher than that of seven other species of wood. After pine was treated by eight different methods, the pine wood treated repeatedly (three times) by the method of dipping 24 hours in water and drying in the sun (SD method) was significantly preferred by C. formosanus. When adding 30% sugar into water for treatment of pine wood blocks in the SD method, the pine wood blocks attracted more termites to feed compared to other concentrations of sugar in water. Moreover, Adding 10% Formosan subterranean termite nest material into 30% sugar solution increased the preference to the treated pine wood blocks by C. formosanus. This information shows that C. formosanus likes to feed on pine wood blocks treated repeatedly by the method of dipping in mixed solutions of Formosan subterranean termite nest material and 30% sugar for 24 hours and drying in the sun.

Development of Long-Term Storage Technology for Chinese Cabbage - Physiological Characteristics of Postharvest Freshness in a Cooler with a Monitoring and Control Interface

Purpose: The aim of this study was to develop long-term storage technology for Chinese cabbage in order to extend the period of availability of freshly harvested products. The scope of the paper deals with the use of a cooler with a remote monitoring and control interface in conjunction with use of packaging film. Methods: A cooler with a real time monitoring system was designed as a low-temperature storage facility to control temperature and relative humidity (RH). The effects of storage in high-density polyethylene (HDPE) plastic boxes, 3% chitosan dipping solution, polypropylene film (PEF) with perforations, and mesh packaging bags on physiological responses were investigated. The optimal storage temperature and humidity for 120 days were below 0.5°C and 90%, respectively. Physiological and biochemical features of cabbage quality were also analyzed: weight loss, texture, and sugar salinity, chlorophyll, reducing sugar, and vitamin C contents. Results: The cooler with a remote monitoring and control interface could be operated by an HMI program. A 0.5°C temperature and 90% humidity could be remotely controlled within the cooler for 120 days. Postharvest freshness of Chinese cabbages could be maintained up to 120 days depending on the packaging method and operation of the remote monitoring system. In particular, wrapping the cabbages in PEF with perforations resulted in a less than a 5% deterioration in quality. This study provides evidence for efficient performance of plastic films in minimizing post-harvest deterioration and maintaining overall quality of cabbages stored under precise low-temperature conditions with remote monitoring and a control interface. Conclusions: Packaging with a modified plastic film and storage in a precisely controlled cooler with a remote monitoring and control interface could slow down the physiological factors that cause adverse quality changes and thereby increase the shelf life of Chinese cabbage.

COMPARISON OF DIFFERENT WAYS OF CHROMATOGRAPHIC SPOTS VISUALIZATION IN DETERMINATION OF ANTYHISTAMINE SUBSTANCES

Importance of compounds investigated (loratadine, desloratadine, cetirizine dihydrochloride, levocetirizinedihydrochloride) i n contemporary pharmacy causes necessity of finding the fast and easy method for their identifi cation. The aim of this work is to find the best way of visualization of chromatographic spots in qualitative determination of compounds investigated during analysis by thin layer chromatography. The standard solution s of compounds investigated were prepar ed in ethanol or methanol. The different mobile phases for particular compounds were used. There were also used many ways of spot visualization i.e. exposure to UV light, dipping in solution of visualizing agents, visualization in iodine vapour and photo c atalytic visualization. The best visualization effect gave exposure to UV light and dipping in solution of bromophenol blue in the case of loratadine and desloratadine, respective ly; and visualization in iodine vapour in the case of cetirizine and levoceti rizine. Using photo catalytic degradation had no use in the case all of compounds investigated.

Preparation of Activated Carbon Loaded with Ferric Oxide Hydrate and its Absorption for Arsenic

In this study granular activated carbon loaded with ferric oxide hydrate (Fe-AC) as arsenic adsorbent was prepared by impregnation method. The influence of the kinds of ferric salt solution, the concentration of ferric salt solution, impregnation time and curing temperature on its arsenic removal effect was investigated. The optimal preparation conditions of the adsorbent were determined. And its adsorption properties of arsenic in aqueous solution were studied by static adsorption experiments. Results showed that when the dipping solution is 1.0 mol/L of Fe (NO3)3, impregnation time is 16h and the curing temperature is 60°C, the arsenic adsorption effect of the prepared adsorbent is best. The pattern of adsorption of As (V) with Fe-AC prepared under optimal condition well fit the Langmuir adsorption model, the correlation coefficient R2is greater than 0.98, and the maximum adsorption capacity is up to 71.43 mg/g.

Post-consumer Recycled PET Packaging for Fresh Berries: A Comparative Study between Incorporating an Antifungal Agent Superficially and into the Main Body of the Packaging

This study proposes to incorporate an antifungal agent (potassium sorbate, KS) to post-consumer recycled polyethylene terephthalate (PCRPET), by adding KS to the dip solution through which PCRPET normally passes after extrusion, in order to acquire a non-stick silicone coating, which prevents individual packages from adhering to each other while stacked. This method of imparting antifungal activity to the packaging is far more advantageous than adding KS to the extruder feed because it results in virtually no alterations to the colour and mechanical properties of PCRPET, which is a major issue when KS is added to the extruder feed. The antifungal efficacy of the active packaging was demonstrated against Botrytis cinerea growth by a novel method which mimics the action of the antifungal agent under fruit contact conditions. A reduction by 2 log cycles was observed when the initial concentration of the mould was 105 conidia/mL. The active packaging was effective over a test period lasting 6 months. The packaging microstructure was visualized by scanning electron microscopy (SEM); its thermal properties were characterized using a differential scanning calorimeter (DSC); its optical properties were characterized using CIE Lab colorimetry; and its mechanical properties were characterized by measuring resistance to dynamic compression. The mechanical properties showed no significant difference (P > 0.05) with those of the control (PCRPET without KS), and despite a statistically significant difference (P < 0.05) in the colour parameters (L*, a* and b*), the total colour difference (ΔE*) was found to be too small to be visually noticed. This study achieved the aim of adding antifungal activity to PCRPET packaging with little or no perceptible changes to its mechanical, thermal and optical properties and virtually no changes being made to the standard high-speed packaging production line.

Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite.

Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments.

Physico-Chemical Study of Coating Formulation Based on Natural Apatite for the Elaboration of Microfiltration Membrane

This work deals with the experimental characterization of the rheological properties of a dip solution which will be used to elaborate a new apatite/clay microfiltration membrane by deposition using slip casting process of the active layer on a tubular support based on natural clay previously prepared. So, the rheological study of various coatings with different concentration of apatite powder, polyvinyl alcohol (PVA) and water under different conditions regarding temperature and stirring time was done. It was found that the suitable suspension should follow a rheo- thickner behavior having a viscosity in the range of 30-35 mPa s at room temperature of 25 to 30°C. The optimum conditions then found to achieve these properties were: a suspension of 4% of apatite, 40% of PVA stirred for 180minutes. The study reveals also that the thickness of the active membrane layer depends on the coating time.

Silicon‐Encapsulated Hollow Carbon Nanofiber Networks as Binder‐Free Anodes for Lithium Ion Battery

Silicon‐encapsulated hollow carbon nanofiber networks with ample space around the Si nanoparticles (hollow Si/C composites) were successfully synthesized by dip‐coating phenolic resin onto the surface of electrospun Si/PVA nanofibers along with the subsequent solidification and carbonization. More importantly, the structure and Si content of hollow Si/C composite nanofibers can be effectively tuned by merely varying the concentration of dip solution. As‐synthesized hollow Si/C composites show excellent electrochemical performance when they are used as binder‐free anodes for Li‐ion batteries (LIBs). In particular, when the concentration of resol/ethanol solution is 3.0%, the product exhibits a large capacity of 841 mAh g−1 in the first cycle, prominent cycling stability, and good rate capability. The discharge capacity retention of it was ~90%, with 745 mAh g−1 after 50 cycles. The results demonstrate that the hollow Si/C composites are very promising as alternative anode candidates for high‐performance LIBs.

Vertical Arrays of SiO2 Micro/Nanotubes Templated from Si Pillars by Chemical Oxidation for High Loading Capacity Buoyant Aquatic Devices

A simple and facile method to fabricate SiO2 micro- or nanotubes has been demonstrated based on room temperature wet chemical oxidation of a porous layer of Si pillar templates that have been prepared by metal-assisted chemical etching (MaCE). Under typical conditions, Si pillars produced by the MaCE have been found to be covered with a thin nanoporous Si layer. The porous Si skin layer has been chemically oxidized by simple dipping in AgNO3 solution at room temperature, which has led to seamless SiO2 shell layer thanks to the accompanying volume expansion during the wet oxidation. Following wet removal of core Si by KOH yields the SiO2 micro- or nanotubes, either in test tube shape or in open shape at both ends, depending on processing method. The vertical arrays of the SiO2 tube on the Si substrate, after hydrophobic siloxane oligomer printing, has been found to have very large loading capacity on water, due to extremely high porosity (>90%) and good enough mechanical stability. The novel method to fabricate SiO2 tubes can shed new light in design of novel aquatic devices, other than simple mimicking the leg of a water strider. Also, the method may be very helpful in various applications of SiO2 nanotubes.