Room Temperature Storage Time Research Articles

Thermo‐responsive macroporous p(NIPAM) cryogel affords enhanced thermal stability and activity for ɑ‐glucosidase enzyme by entrapping in situ

AbstractThe concept of using a macroporous thermo‐responsive poly(N‐isopropylacrylamide) (p(NIPAM)) polymer matrix for enzyme immobilization having lower critical solution temperature (LCST) is rationalized by the availability of the many compartments (pores) to entrap enzymes to operate within pores of three‐dimensional matrix providing special environmental conditions. Therefore, the ɑ‐glucosidase (ɑ‐G) immobilization within p(NIPAM) cryogel (ɑ‐G@p(NIPAM)) was carried out under the storage conditions of enzymes, generally ~ −20°C to afford the unnecessary loss of enzyme functionality in comparison to the other enzyme entrapment methods. The LCST value for the prepared p(NIPAM)‐based cryogels was determined as 34.8 ± 1.4°C. The immobilization yield, immobilization efficiency, and activity recovery% values were calculated as 89.4 ± 3.1, 66.2 ± 3.3, and 74.0% ± 3.3%, respectively, at pH 6.8 and 37°C for ɑ‐G@p(NIPAM) cryogel system. Interestingly, the optimum working conditions were attained as 25°C and pH 6.8 with higher activity, 98.4% ± 0.2% for the prepared ɑ‐G@p(NIPAM) cryogel system. The reuse and storage stability studies revealed that the prepared ɑ‐G@p(NIPAM) cryogel system is more effective than the native ɑ‐G enzyme; for example, it showed at least 80% activity after the fifth usage and provided higher activity up to a 10‐day room temperature storage time. Moreover, the kinetic parameters such as Km and Vmax of native ɑ‐G enzyme and ɑ‐G@p(NIPAM) cryogel system were calculated by non‐linear Lineweaver–Burk plot equations.

Physical, Chemical, and Sensory Characteristics of Frozen Salted Edamame During Storage at Room Temperature

Edamame soybeans are a superior product in Jember Regency. Edamame has the advantage of protein, calcium and iron content. In general, edamame soybeans are a perishable food commodity that must be processed immediately. One of the processed edamame products is frozen salted edamame which is a practical ready-to-eat snack. Frozen salted edamame has attracted the interest of the people of Jember and people outside the city. This product is popular with people outside the city, so they often buy it to take home as a souvenir from Jember Regency. Uncontrolled environmental conditions during the trip with sudden temperature changes without cold storage cause the potential for physical damage or deterioration of quality in frozen salted edamame. Therefore, further observations are needed to determine changes in the quality of frozen salted edamame products during the trip without cold storage at room temperature storage. The purpose of this study was to determine the effect of room temperature storage time on physical quality, chemical quality, and organoleptic quality of frozen salted edamame products. The design of this study used a completely randomized design with a single factor, namely five treatments for different durations (0 hours, 12 hours, 24 hours, 36 hours, and 48 hours after removed from the freezer). The analyzes carried out in this study were the test of texture, color, pH, total dissolved solids, total acid, antioxidant activity, moisture content, and organoleptics. The results showed that the frozen salted edamame product decreased during storage time at room temperature. Based on the results of research, the duration of storage for frozen salted edamame products at room temperature has an effect on the value of color, pH, total dissolved solids, total acid, and water content, but does not affect the texture and antioxidant activity. The quality of the product also decreased in color, taste, aroma, and texture attributes.

230 s room-temperature storage time and 1.14 eV hole localization energy in In0.5Ga0.5As quantum dots on a GaAs interlayer in GaP with an AlP barrier

A GaP n+p-diode containing In0.5Ga0.5As quantum dots (QDs) and an AlP barrier is characterized electrically, together with two reference samples: a simple n+p-diode and an n+p-diode with AlP barrier. Localization energy, capture cross-section, and storage time for holes in the QDs are determined using deep-level transient spectroscopy. The localization energy is 1.14(±0.04) eV, yielding a storage time at room temperature of 230(±60) s, which marks an improvement of 2 orders of magnitude compared to the former record value in QDs. Alternative material systems are proposed for still higher localization energies and longer storage times.

Modelling the Combined Effect of Room Temperature Storage and Cold Deformation on the Age-Hardening Behaviour of Al-Mg-Si Alloys-Part 2

The present investigation deals with modelling of the age-hardening behaviour of 6xxx series automotive sheet alloys. The basis for this work is the established precipitation model NaMo developed for coupled nucleation, growth, dissolution and coarsening in Al-Mg-Si extrusion alloys. It has recently been extended for applicability for Al-Mg-Si automotive sheet alloys by incorporating the important effects of room temperature (RT) storage and deformation prior to the final artificial ageing of Al-Mg-Si sheet alloys. The 6xxx automotive sheet alloys change due to natural ageing during the time elapsing between their processing and their paint baking in the customers process. This RT storage time has an impact on the artificial ageing response during the OEMs paint baking cycle. A second effect originates from the deformation introduced in the material during the part forming process prior to the artificial ageing in the paint bake cycle. This deformation leads to the introduction of dislocations which further modify the artificial ageing response by providing heterogeneous nucleation sites for nucleation of additional strengthening phases. Part 1 of this work deals with the theoretical background and experimental validation of the extended version of NaMo, while Part 2 focuses on the new applications of the extended model by simulation of ageing during paint baking according to typical customer requirements. The model validation is based on a comprehensive set of tensile tests. A comparison between model predictions and measurements shows reasonable agreement, and it is concluded that, after some further development, the model can be used to model the yield strength response of 6xxx automotive sheet alloys incorporating the (combined) effects of natural ageing, deformation and the accurate heat treatments in the paint bake cycle.

Quality Control Methods for Optimal BCR-ABL1 Clinical Testing in Human Whole Blood Samples

Reliable breakpoint cluster region (BCR)--Abelson (ABL) 1 measurement is essential for optimal management of chronic myelogenous leukemia. There is a need to optimize quality control, sensitivity, and reliability of methods used to measure a major molecular response and/or treatment failure. The effects of room temperature storage time, different primers, and RNA input in the reverse transcription (RT) reaction on BCR-ABL1 and β-glucuronidase (GUSB) cDNA yield were assessed in whole blood samples mixed with K562 cells. BCR-ABL1 was measured relative to GUSB to control for sample loading, and each gene was measured relative to known numbers of respective internal standard molecules to control for variation in quality and quantity of reagents, thermal cycler conditions, and presence of PCR inhibitors. Clinical sample and reference material measurements with this test were concordant with results reported by other laboratories. BCR-ABL1 per 10(3) GUSB values were significantly reduced (P = 0.004) after 48-hour storage. Gene-specific primers yielded more BCR-ABL1 cDNA than random hexamers at each RNA input. In addition, increasing RNA inhibited the RT reaction with random hexamers but not with gene-specific primers. Consequently, the yield of BCR-ABL1 was higher with gene-specific RT primers at all RNA inputs tested, increasing to as much as 158-fold. We conclude that optimal measurement of BCR-ABL1 per 10(3) GUSB in whole blood is obtained when gene-specific primers are used in RT and samples are analyzed within 24 hours after blood collection.

Determination of dosimetric and kinetic features of gamma irradiated solid calcium ascorbate dihydrate using ESR spectroscopy

Effects of gamma radiation on solid calcium ascorbate dihydrate were studied using electron spin resonance (ESR) spectroscopy. Irradiated samples were found to present two specific ESR lines with shoulder at low and high magnetic field sides. Structural and kinetic features of the radicalic species responsible for experimental ESR spectrum were explored through the variations of the signal intensities with applied microwave power, variable temperature, high-temperature annealing and room temperature storage time studies. Dosimetric potential of the sample was also determined using spectrum area and measured signal intensity measurements. It was concluded that three radicals with different spectroscopic and kinetic features were produced upon gamma irradiation.

Effect of room temperature storage time on precipitation in Al–Mg–Si(–Cu) alloys with different Mg/Si ratios

Abstract The effect of natural ageing time before artificial ageing has been investigated in four Al–Mg–Si(–Cu) alloys, with 0.4% Mg + 0.8% Si and 0.8% Mg + 0.4% Si, both with and without 0.14 at.% Cu. The precipitate microstructure was quantified by means of transmission electron microscopy. Varying the storage time before ageing for 170 min at 200°C, we observe an initial hardness increase after minutes, a decrease after several hours and another increase after weeks. The hardness decrease was most pronounced in the Mg-rich Cu-free alloy, caused by a reduced precipitate volume fraction. Adding Cu produces finer microstructures, higher hardness and reduces the negative effect of natural ageing regardless of the Mg/Si ratio of the alloy. With 1 week storage, an increase in the fraction of the Cu-containing precipitates L and Q′ was observed in the Cu-containing Si-rich and Mg-rich alloys respectively.

Kinetics of the radiation-induced radical species in gamma irradiated solid sodium ascorbate

In the present work, radicals induced in γ-irradiated solid sodium ascorbate (SA) were studied by electron spin resonance (ESR) spectroscopy. While unirradiated samples presented no ESR signal, irradiated samples were found to present a spectrum of an unresolved doublet with a shoulder at the low-magnetic field side. Structural and kinetic features of the radical species responsible for the experimental ESR spectrum were explored through the variations of the signal intensities associated with spectrum maxima and minima with applied microwave power, sample temperature, and room temperature storage time. Activation energies of the involved species were also determined using the data derived from annealing studies performed at high temperatures. Produced radical species were observed to be relatively stable at room temperature. This gave the opportunity to distinguish irradiated SA or SA containing irradiation products from unirradiated ones even long after irradiation. SA presented also the features of a dosimetric material, which could be used in the estimation of dose range in accidental dosimetry.

Hematopoietic Lineage Transcriptome Stability and Representation in PAXgene™ Collected Peripheral Blood Utilising SPIA Single-Stranded cDNA Probes for Microarray

Peripheral blood as a surrogate tissue for transcriptome profiling holds great promise for the discovery of diagnostic and prognostic disease biomarkers, particularly when target tissues of disease are not readily available. To maximize the reliability of gene expression data generated from clinical blood samples, both the sample collection and the microarray probe generation methods should be optimized to provide stabilized, reproducible and representative gene expression profiles faithfully representing the transcriptional profiles of the constituent blood cell types present in the circulation. Given the increasing innovation in this field in recent years, we investigated a combination of methodological advances in both RNA stabilisation and microarray probe generation with the goal of achieving robust, reliable and representative transcriptional profiles from whole blood. To assess the whole blood profiles, the transcriptomes of purified blood cell types were measured and compared with the global transcriptomes measured in whole blood. The results demonstrate that a combination of PAXgene() RNA stabilising technology and single-stranded cDNA probe generation afforded by the NuGEN Ovation RNA amplification system V2() enables an approach that yields faithful representation of specific hematopoietic cell lineage transcriptomes in whole blood without the necessity for prior sample fractionation, cell enrichment or globin reduction. Storage stability assessments of the PAXgene() blood samples also advocate a short, fixed room temperature storage time for all PAXgene() blood samples collected for the purposes of global transcriptional profiling in clinical studies.

Self-annealing of electrodeposited copper thin film during room temperature storage

Abstract The electrodeposition of copper on steel substrates has been used to produce a relative thick copper film. The resistivity and rigidity of the copper film are the key parameters for practical applications of the Fe/Cu composite. In this study, the electrodeposition of copper on steel substrate was performed at varied cathode current densities of 2∼14 A·dm − 2 . The resistivity and rigidity of the electrodeposited copper film increased with current density, while decreased with room temperature storage time due to the increase of crystal grain size and decrease of grain boundary number.

A comparison study: The new extended shelf life isopropyl ester PMR technology versus the traditional methyl ester PMR approach

AbstractPolymerization of monomeric reactants (PMR) monomer solutions and carbon cloth prepregs of PMR II‐50 and VCAP‐75 were prepared using both the traditional limited shelf life methanol based PMR approach and a novel extended shelf life isopropanol based PMR approach. The methyl ester and isopropyl ester based PMR monomer solutions and PMR prepregs were aged for up to 4 years at freezer and room temperatures. The aging products formed were monitored using high pressure liquid chromatography (HPLC). The composite processing flow characteristics and volatile contents of the aged prepregs were correlated versus room temperature storage time. Composite processing cycles were developed and six‐ply cloth laminates were fabricated with prepregs after various extended room temperature storage times. The composites were then evaluated for glass transition temperature (Tg), thermal decomposition temperature (Td), initial flexural strength (FS), and modulus (FM), long term (1000 h at 316°C) thermal oxidative stability (TOS), and retention of FS and FM after 1000 h aging at 316°C. The results for each ester system were comparable. Freezer storage was found to prevent the formation of aging products for both ester systems. Room temperature storage of the novel isopropyl ester system increased PMR monomer solution and PMR prepreg shelf life by at least an order of magnitude, while maintaining composite thermal and mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3549–3564, 2006

Influence of thermal treatments on the response decay of glass radiation detectors.

Commercial transparent glass has received attention in relation to its use as a gamma radiation detector. This kind of material presents a strong post-irradiation thermal decay at room temperature, which is a problem for high dose dosimetry purposes. This effect may be avoided by taking measurements always at the same time after irradiation of the glass samples. However, in this work effort has been given to this material characteristic, submitting the glass samples to different thermal treatments. The best results were obtained with a post-irradiation treatment at 130 degrees C during 10 min. This procedure seems to destroy the unstable entities responsible for the initial strong decay of the sample response, showing acceptable stability as a function of room temperature storage time.

The Influence of Block Copolymers on Silica-Filled Polyisoprene

ABSTRACTThe influence of PDMS-polyisoprene diblock copolymers on the dynamic rheological properties of silica-filled uncured polyisoprene was investigated. Unlike binary silica-polyisoprene systems, the ternary systems in our study showed a decrease in low-amplitude dynamic storage modulus (G') with room-temperature storage time. This aging behaviour is accompanied by an increase in the concentration PDMS segments at the filler-polymer interface, as measured by solid-state 1H NMR. The decrease in G' is thus attributed to a progressive disruption of a filler-filler network by selective block copolymer adsorption onto the filler surface.

Dynamic charge storage in 6H silicon carbide

pn-junction storage capacitors have been fabricated in 6H silicon carbide. The charge decay is dominated by surface generation at the mesa edges, and the storage time strongly depends on the method of surface passivation. Charge recovery is thermally activated. Devices passivated by dry oxidation and by wet oxidation exhibit activation energies of 0.66 and 1.48 eV, respectively. As a figure of merit, extrapolation of the dry-oxide data gives a room-temperature storage time of 106 s, while extrapolation of the wet-oxide data gives a room-temperature storage time of 1014 s.

Characterization of a GaAs/AlGaAs modulation-doped dynamic random access memory cell

We report the electrical properties of a GaAs dynamic random access memory (DRAM) cell in which the storage capacitor is a modulation-doped heterojunction and the access transistor is a modulation-doped field-effect transistor. Experimental waveforms illustrating both reading and writing are exhibited. Isolated storage capacitors have 1/e storage times as long as 4.3 h at room temperature. The complete DRAM cell exhibits a room temperature storage time of about 3 min, limited by gate leakage in the access transistor.

Dynamic charge storage in 6H-silicon carbide: prospects for high-speed nonvolatile RAMs

Summary form only given. Charge storage on p-n junctions in 6H-silicon carbide (SiC) has been investigated. Storage times in these devices are too long to be measured at room temperature, and most investigations were conducted at temperatures above 300 degrees C. Charge recovery in this regime is thermally activated with an activation energy close to half bandgap ( approximately=1.45 eV). Studies of different size devices indicate that the leakage current is dominated by generation at the SiO/sub 2/ passivated sidewalls, and is sensitive to the oxidation conditions (i.e., wet versus dry). A simple extrapolation of the high-temperature data yields a room-temperature storage time of several hundred thousand years. >

Mechanical properties of oriented polyethylene/polystyrene blends

AbstractIncompatible blends comprised of polystyrene and various high density polyethylenes were processed into tapes, in which both the phase and molecular orientations were parallel to the machine direction, by a combination of extrusion and mechanical stretching of the melt prior to quenching. Machine direction tensile yield strengths and ultimate elongations were found to be considerably higher than those obtained for comparable compression molded samples throughout the range of blend compositions and processing conditions investigated. Transverse tape properties were consistently poor due to poor interfacial adhesion. An optimum in machine direction properties was observed as the stretch ratio was increased at various melt temperatures. This optimum is likely due to a competition between morphological and molecular orientation rates during the stretching process and is a complex function of stretching rate and melt temperature as well as blend composition, relative phase viscosities, polyethylene crystallinity, and interfacial adhesion. Tapes stretched at high melt temperatures tended to show decreasing ductility and increasing tensile strength as room temperature storage time increased. This is believed to be due to secondary crystallization of the polyethylene phase. Oriented tapes were found to be easily fibrillated by mechanical heating to form a pulp. This material may prove suitable as a high grade replacement for cellulose pulp in paper making and could be formed at low cost from waste plastic feed stock.