Rigid Container Research Articles

Morphophysiological quality of yerba mate plantlets produced by mini-cuttings

The objective of this study was to evaluate the morphophysiological quality of yerba mate plantlets (Ilex paraguariensis A. St.-Hil.) produced by mini-cutting at four different times of year and cultivated in different containers. For the rooting of mini-cuttings, shoots of four yerba mate clones were collected four times during the year (April, July and October 2014 and January, 2015), cut into single-budded mini-cuttings and planted in equal proportions of pine bark-based commercial substrate, vermiculite and coarse sand. After 60 days of cultivation in a wet chamber, the rooted mini-cuttings were transferred to different containers: a 100 cm³ rigid polyethylene tube container and 500, 1500 and 3000 cm3 polyethylene bags containing pine bark-based commercial substrate and underground soil (2:1 v/v). A completely randomized design was used in a 4 x 4 factorial scheme, with five replications ranging from 5 to 20 mini-cuttings per experimental unit. The plantlets were evaluated for survival percentage, shoot height, stem diameter, shoot height/stem diameter ratio and number of leaves at 30, 60, 90 and 120 days of cultivation. At 120 days of cultivation, 10 plantlets from each treatment were randomly picked to evaluate shoot and root dry mass, Dickson quality index, shoot height, surface area, total volume and number of root tips. The best combinations of shoot height, length, surface area, total volume and number of root tips and Dickson quality index were found in plantlets produced in July, 2014, followed by plantlets produced in October,2014 and January, 2015. The polyethylene bags allowed the production of yerba mate plantlets with satisfactory quality of shoot and roots, regardless of the volume. Yerba mate plantlets can be produced by mini-cutting from July to January in polyethylene bags.

Effect of Particle Morphology, Compaction, and Confinement on the High Strain Rate Behavior of Sand

The effect of grain shape, size distribution, intergranular friction, confinement, and initial compaction state on the high strain rate compressive mechanical response of sand is quantified using Long Split Hopkinson Pressure Bar (LSHPB) experiments, generating up to 1.1 ms long load pulses. This allowed the dynamic characterisation of different types of sand until full compaction (lowest initial void ratio) at different strain rates. The effect of the grain morphology and size on the dynamic compressive mechanical response of sand is assessed by conducting experiments on three types of sand: Ottawa Sand with quasi-spherical grains, Euroquartz Siligran with subangular grains and Q-Rok with polyhedral grain shape are considered in this study. The adoption of rigid (Ti64) and deformable (Latex) sand containers allowed for quasi-uniaxial strain and quasi-uniaxial stress conditions to be achieved respectively. Additionally, the effect of intergranular friction was studied, for the first time in literature, by employing polymer coated Euroquartz sand. Appropriate procedures for the preparation of samples at different representative initial consolidation states are utilized to achieve realistic range of naturally occurring formations of granular assembly from loose to dense state. The results identify material and confining sample state parameters which have significant effect on the mechanical response of sand at high strain rates and their interdependency for future integration into rate dependent constitutive models.

LEAP-GWU-2015 experiment specifications, results, and comparisons

LEAP (Liquefaction Experiments and Analysis Projects) is an effort to formalize the process and provide data needed for validation of numerical models designed to predict liquefaction phenomena. For LEAP-GWU-2015, one project within LEAP, an experiment was repeated at 6 centrifuge facilities (Cambridge University, Kyoto University, University of California Davis, National Central University, Rensselaer Polytechnic Institute, and Zhejiang University) and the results were shared and archived for the purposes of validation of numerical models. This paper describes the specifications for the LEAP-GWU-2015 experiment and compares the experimental results from the six facilities. The specified experiment was for uniform medium dense sand with a 5 degree slope in a rigid container subject to a ramped, 1Hz sine wave base motion. The experiment was meant to be relatively simple to enable different facilities to produce comparable experiments. Although it cannot be claimed that identical experiments were precisely replicated on different centrifuges, it is argued that the results are similar enough that each experiment lends veracity to the set of results. A benefit of variability between experiments is that the variety enables a more general validation. Important lessons with regard to specification of future experiments for validation of numerical models are summarized. LEAP-GWU-2015 has demonstrated an approach that is a useful reference for future validation studies.

Completeness of inertial modes of an incompressible inviscid fluid in a corotating ellipsoid.

Inertial modes are the eigenmodes of contained rotating fluids restored by the Coriolis force. When the fluid is incompressible, inviscid, and contained in a rigid container, these modes satisfy Poincaré's equation that has the peculiarity of being hyperbolic with boundary conditions. Inertial modes are, therefore, solutions of an ill-posed boundary-value problem. In this paper, we investigate the mathematical side of this problem. We first show that the Poincaré problem can be formulated in the Hilbert space of square-integrable functions, with no hypothesis on the continuity or the differentiability of velocity fields. We observe that with this formulation, the Poincaré operator is bounded and self-adjoint, and as such, its spectrum is the union of the point spectrum (the set of eigenvalues) and the continuous spectrum only. When the fluid volume is an ellipsoid, we show that the inertial modes form a complete base of polynomial velocity fields for the square-integrable velocity fields defined over the ellipsoid and meeting the boundary conditions. If the ellipsoid is axisymmetric, then the base can be identified with the set of Poincaré modes, first obtained by Bryan [Philos. Trans. R. Soc. London 180, 187 (1889)PTRMAD1364-503X10.1098/rsta.1889.0006], and completed with the geostrophic modes.

Large-volume constant-concentration sampling technique coupling with surface-enhanced Raman spectroscopy for rapid on-site gas analysis

In this work, a portable large-volume constant-concentration (LVCC) sampling technique coupling with surface-enhanced Raman spectroscopy (SERS) was developed for the rapid on-site gas analysis based on suitable derivatization methods. LVCC sampling technique mainly consisted of a specially designed sampling cell including the rigid sample container and flexible sampling bag, and an absorption-derivatization module with a portable pump and a gas flowmeter. LVCC sampling technique allowed large, alterable and well-controlled sampling volume, which kept the concentration of gas target in headspace phase constant during the entire sampling process and made the sampling result more representative. Moreover, absorption and derivatization of gas target during LVCC sampling process were efficiently merged in one step using bromine-thiourea and OPA-NH4+ strategy for ethylene and SO2 respectively, which made LVCC sampling technique conveniently adapted to consequent SERS analysis. Finally, a new LVCC sampling-SERS method was developed and successfully applied for rapid analysis of trace ethylene and SO2 from fruits. It was satisfied that trace ethylene and SO2 from real fruit samples could be actually and accurately quantified by this method. The minor concentration fluctuations of ethylene and SO2 during the entire LVCC sampling process were proved to be <4.3% and 2.1% respectively. Good recoveries for ethylene and sulfur dioxide from fruit samples were achieved in range of 95.0–101% and 97.0–104% respectively. It is expected that portable LVCC sampling technique would pave the way for rapid on-site analysis of accurate concentrations of trace gas targets from real samples by SERS.

Zhejiang University benchmark centrifuge test for LEAP-GWU-2015 and liquefaction responses of a sloping ground

A dynamic centrifuge model test of mildly sloping ground was conducted at Zhejiang University according to the LEAP-GWU-2015 experiment specifications. A 5-degree slope consisting of a saturated medium dense Ottawa F-65 sand was prepared by air pluviation method in rigid container, which simulated a prototype with a 20m length and 4m depth under 26g centrifugal acceleration. The model was subjected to three smaller and two destructive motions. Test data and preliminary analyses of model responses during multiple shakings are presented. In-flight measurement of shear wave velocity by bender elements was used to characterize the evolution of soil state. Acceleration response spectra were presented and site amplification effects were observed. Shear stress-strain loops were calculated from acceleration records, and asymmetric dilatancy in the sloping ground was observed during liquefaction. Generation and dissipation of excess pore pressure were depicted. Large liquefaction-induced ground displacements were measured and analyzed. This study provides valuable data and delivers some important observations of liquefaction responses of a sloping ground.

TROCAS GASOSAS E GRAU DE TOLERÂNCIA AO ESTRESSE HÍDRICO INDUZIDO EM PLANTAS JOVENS DE &lt;i&gt;Tabebuia aurea&lt;/i&gt; (PARATUDO) SUBMETIDAS A ALAGAMENTO

O paratudo, Tabebuia aurea, é uma árvore típica do Pantanal de Miranda, Mato Grosso do Sul, Brasil, sendo esse local, uma área de inundação sazonal. Para avaliar as trocas gasosas de Tabebuia aurea sob estresse hídrico por alagamento, grupos de plantas com oito meses de idade foram mantidas em vasos com o solo coberto por uma lâmina de 2 a 3 cm de água. As taxas de condutância estomática, transpiração e fotossíntese foram determinadas durante o período de experimento (115 dias), através de um analisador portátil de gás infravermelho. Os valores de condutância estomática no início do experimento estavam em torno de 0,22 mol m-2 s-1 e foram decrescendo até 0,02 mol m-2 s-1. Em relação à fotossíntese líquida, o valor máximo inicial foi de 8,0 mmol m-2 s-1, atingindo zero no 108º dia. Após redução em 100% da fotossíntese líquida, as plantas foram retiradas da condição de alagamento e avaliadas (8 dias). Os valores obtidos ao final do processo de recuperação para condutância estomática foram: 0,21 mol m-2 s-1 e fotossíntese = 8,0 mmol m-2 s-1. O alagamento do solo reduziu a fotossíntese, a condutância estomática e afetou o crescimento da parte aérea, induzindo o aparecimento de sintomas característicos de estresse por inundação, como a hipertrofia das lenticelas. Porém, a espécie apresenta tolerância ao estresse, indicando adaptabilidade a áreas sujeitas a alagamento periódico.

LEAP-GWU-2015 centrifuge test at UC Davis

For the LEAP-GWU-2015 exercise, a relatively simple centrifuge test was conducted in parallel at 6 centrifuge facilities including the University of California Davis (UCD). The experiment consisted of a submerged medium dense clean sand with a 5° slope subjected to 1Hz ramped sine wave base motion in a rigid container. This paper explains several details of the experiment at UCD including intended and unintended deviations from the specification and the implementation of new techniques for measurement of saturation of the centrifuge model. One unintended critical deviation was the use of pore fluid that was more viscous than specified; this had significant effect on the pore pressure dissipation time. The other important deviation from the specification was the incomplete ground motion sequence. While it is not ideal for purposes of determining the replicability of centrifuge tests, the differences between experiments diversifies the data available for validation of numerical models.

Prediction of LEAP centrifuge test results using a pressure-dependent bounding surface constitutive model

In accordance with the “Liquefaction Experiments and Analysis Projects (LEAP )” guidelines, class-A, B and C predictions are performed for the response of centrifuge tests on a sloped configuration of Ottawa-F65 soil in a rigid container. The objective of this paper is to discuss important aspects on the calibration process of a pressure-dependent bounding surface constitutive model for the simulation of centrifuge experiments. The constitutive model used in this study is based on the theory of Critical State Soil Mechanics that has shown to be suitable to represent the behavior of cohesionless soils. Results of class-A predictions match experiment data reasonably well. An attempt is made to find a single set of material parameters to be used for class-B and class-C prediction of all six centrifuge tests.

Reducing grain storage losses in developing countries

We investigated the use of insecticide-treated material and modified atmosphere storage for reducing insect damage in stored maize. Results showed that insecticide-treated netting and insecticide-treated seed bags protected grain from insect damage, with the treated seed bags protecting grain for up to nine months if the grain was free from insects before storing. Covering the opening of grain storage containers with treated netting provided good control of stored-grain insects and may offer additional protection for grain silos being promoted in developing countries. Neither treated bags nor netting provided control if the grain contained insects before storage, thus emphasising the need to provide some means of controlling initial infestations at the time of storage when using bags or netting. We also showed that good control of insects can be achieved if the grain is stored in air-tight rigid containers that cannot be penetrated by insects or rodents. Hermetic plastic bags were readily penetrated by in...

Kimchi Packaging Technology : An Overview

This paper provides an overview of kimchi packaging technology, focusing on packaging materials, package design, and active/intelligent packaging technology for kimchi. From a packaging-material standpoint, although various materials have been used to ensure customer satisfaction and convenience, plastic is the most widely used material, in the form of bags, trays, pouches, and rigid containers. Additionally, recent efforts in the kimchi packaging industry have allowed companies to differentiate their products by using different packaging materials and technologies, while simul-taneously improving product safety and quality. On the other hand, the biggest problem in kimchi packaging is excess CO2 production, leading to package expansion and leakage. To alleviate this problem, the use of CO2 absorbers, high CO2-permeable films, and degassing valves, in addition to the use of different packaging systems, has been investigated. Active and/or intelligent packaging systems have been developed, to include active functions beyond simply inert, passive containment and protection of the kimchi product. However, most such approaches are not yet adequately effective to be useful on a commercial scale. Therefore, further studies are needed to resolve the limitations of each technology.

Electrostatic hazards during stirring of flammable organic solvents and suspensions in electrostatically protected plastic containers

At present, stirring of flammable liquids in rigid intermediate bulk containers (RIBCs) is allowed only if, firstly, the RIBC is electrostatically protected and secondly either a liquid such us water-based paint is used or the RIBC is inerted. To verify the necessity of these restrictions, several experimental setups were created to investigate the charging of stirred liquids and suspensions. The following questions were answered: 1) Which liquids/suspensions charge the most during stirring? 2) Is ethyl acetate a special charge accumulator? 3) Which safety measures are necessary for safe stirring in RIBCs?

Dynamics of rectangular tank with perforated vertical baffle

Slosh dynamics of liquid filled tanks is of paramount importance in the study of fluid-structure interaction. Since beginning sectors and compartments are used in fuel tanks of rockets and massive sea ferrying liquid carriers to control dynamic properties of liquid filled tanks. Compartmentalization is also considered essential to control yaw and pitching of sea vessels by controlling bilge water level. However, Solid partition walls are subjected to considerably high hydrodynamic loads and require increased thickness of material thereby causes increased cost and weight. Perforation is one of the methods for reducing ill effects of compartmentalization. Perforation reduces pressure drop across the baffle which in turn reduces required structural strength of the baffle. Screens with optimum perforation placed appropriately may ensure greater dynamic stability without reduction in damping. Screens are widely used as damping devices in TLD in structural engineering, as Propellant Management and Acquisition Devices (PMAD) in aerospace engineering.Several experimental and theoretical studies are carried out to analyze the effects of surface-piercing and bottom-mounted vertical baffles, screens but no well-established numerical method is developed so far. In this paper a finite element method using pressure formulation is adopted to study dynamic properties of rectangular rigid containers with single-slotted internal elements and screens

Thermodynamic Model for Gas Explosions in Vented and Non-Vented Enclosures

ABSTRACTA computer model capable of predicting the thermodynamic properties that occur inside a rigid container during both a non-vented or vented gas explosion is described. The model applies the conservation of mass, energy, and momentum of the combustion gases and the motion of a rigid mass that covers an opening to the enclosure. The computer model differs from others examining similar problems by using a complete energy equation applied to the combustion gases and it includes temperature and pressure varying properties and heat transfer from combustion zone to the enclosure. The fundamental equations are non-dimensionalized resulting in two dimensionless groups that can be used to design an enclosure that will control or mitigate the effects of an explosion. Model results are compared with available experimental measurements of enclosure pressures for vented and non-vented explosions. The model closely predicts the transient pressure rise for explosions of hydrogen, methane, and mixtures of those two gases in a wide range of gas concentrations and for a variety of vessel and vent geometries.

Reason behind wet pack after steam sterilization and its consequences: An overview from Central Sterile Supply Department of a cancer center in eastern India

Wet pack after steam sterilization process that means there are surely obtain millions of microorganisms that can breed and multiply rapidly and objects are unsterile and can never be used for further procedure. There are many reasons behind the wet pack occurrences after autoclaving like poor quality of wrapping materials, faulty valves of rigid container, faulty loading and packaging technique, poor steam quality, sterilizer malfunction and may be design related problems in CSSD sterile storage area. Cause of wet pack after steam sterilization processes may occur severe problems because of wasted time and effort, increased work load, increased cost, potentially contaminated instruments, infection risk to the patient, poor patient outcomes and delayed or cancellation of procedures. But such wet pack scenario can be avoided by various methods by using good steam (water) quality, performing periodic maintenance of the Autoclaves, avoidance of sterilizer overloading, allowing adequate post sterilization time to cool down the materials to room temperature, using good quality wrapping materials, properly maintain temperature and humidity of sterile storage area etc.

Assembly and Mechanical Properties of the Cargo-Free and Cargo-Loaded Bacterial Nanocompartment Encapsulin

Prokaryotes mostly lack membranous compartments that are typical of eukaryotic cells, but instead, they have various protein-based organelles. These include bacterial microcompartments like the carboxysome and the virus-like nanocompartment encapsulin. Encapsulins have an adaptable mechanism for enzyme packaging, which makes it an attractive platform to carry a foreign protein cargo. Here we investigate the assembly pathways and mechanical properties of the cargo-free and cargo-loaded nanocompartments, using a combination of native mass spectrometry, atomic force microscopy and multiscale computational molecular modeling. We show that encapsulin dimers assemble into rigid single-enzyme bacterial containers. Moreover, we demonstrate that cargo encapsulation has a mechanical impact on the shell. The structural similarity of encapsulins to virus capsids is reflected in their mechanical properties. With these robust mechanical properties encapsulins provide a suitable platform for the development of nanotechnological applications.

Clinical Issues—June 2016

Use of alcohol (ethanol)-based hand rubs (ABHRs) during pregnancy Key words: alcohol, ethanol, hand rub, ABHR, hand sanitizer. Working when experiencing a shingles infection Key words: shingles, varicella, zoster, employee health. Cleaning rigid containers Key words: rigid container, container, instrument pan.

Effect of thermal gradients on stress/strain distributions in a thin circular symmetric plate

The analysis of thermally induced stresses in engineering structures is a very important and necessary task with respect to design and modeling of pressurized containers, heat exchangers, aircrafts segments, etc. to prevent them from failure and improve working conditions. So, the purpose of this study is to investigate elasto-plastic thermal stresses and deformations in a thin annular plate embedded into rigid container. To this end, analytical research devoted to mathematically and physically rigorous stress/strain analysis is performed. In order to evaluate the effect of logarithmic thermal gradients, commonly applied to structures which incorporate thin plate geometries, different thermal parameters such as temperature mismatch and varying constraint temperature were introduced into the model of elastic perfectly-plastic annular plate obeying the von Mises yield criterion with its associated flow rule. The results obtained may be used in sensitive to temperature differences aircraft structures where the thermal effects on equipment must be kept in mind.

Palm oil deodorizer distillate as toughening agent in polylactide packaging films

AbstractPolylactide (PLA) is the most used biodegradable and biobased food packaging polymer for rigid containers and films. However, its low ductility is a hurdle for increasing its applications in flexible food packaging. A solution is the use of additives. Palm oil deodorizer distillate (PODC) is revealed to be an excellent additive promoting PLA ductility. PODC is a by‐product of vegetable oil refining, which is available in stable quality and in sufficient amounts. Amorphous PLA/PODC blends had an elongation at break of around 130% and that of semi‐crystalline blends was still around 55% compared to the initial 5% of neat PLA. At the same time the PLA rigidity and high glass transition temperatures were kept. PODC was also a very efficient processing aid, allowing for film blow extrusion. The blends were stable in properties during six months without exudation. They complied with legal norms of Food Contact Materials (EU 10/2011) and induced no sensorial alteration of packed food. Therefore PODC is a very interesting alternative to common plasticizers for the production of flexible PLA packaging films. © 2016 Society of Chemical Industry

Non-linear tides in a homogeneous rotating planet or star: global modes and elliptical instability

We revisit the global modes and instabilities of homogeneous rotating ellipsoidal fluid masses, which are the simplest global models of rotationally and tidally deformed gaseous planets or stars. The tidal flow in a short-period planet may be unstable to the elliptical instability, a hydrodynamic instability that can drive tidal evolution. We perform a global (and local WKB) analysis to study this instability using the elegant formalism of Lebovitz & Lifschitz. We survey the parameter space of global instabilities with harmonic orders $\ell\leq 5$, for planets with spins that are purely aligned (prograde) or anti-aligned (retrograde) with their orbits. In general, the instability has a much larger growth rate if the planetary spin and orbit are anti-aligned rather than aligned. We have identified a violent instability for anti-aligned spins outside of the usual frequency range for the elliptical instability (when $\frac{n}{\Omega}\lesssim -1$, where $n$ and $\Omega$ are the orbital and spin angular frequencies, respectively) if the tidal amplitude is sufficiently large. We also explore the instability in a rigid ellipsoidal container, which is found to be quantitatively similar to that with a realistic free surface. Finally, we study the effect of rotation and tidal deformation on mode frequencies. We find that larger rotation rates and larger tidal deformations both decrease the frequencies of the prograde sectoral surface gravity modes. This increases the prospect of their tidal excitation, potentially enhancing the tidal response over expectations from linear theory. In a companion paper, we use our results to interpret global simulations of the elliptical instability.