Cork Sheets Research Articles

Slate–Cork Laminate Enhanced with Silicone for Habitat Industry Application

This study investigates the feasibility of using a composite material comprising slate reinforced with cork sheets for architectural purposes like facades and wall coverings. The research involves the comprehensive characterisation of both slate and cork materials along with the evaluation of the silicone adhesive used in their bonding process, specifically Sikasil® HT from SIKA®. It was found that both slate and cork exhibited low wettability, which was enhanced through cold plasma treatment. Subsequently, a composite sandwich structure was fabricated and subjected to impact testing in a drop tower, along with fire resistance evaluations. The fire tests revealed that when subjected to a flame of 900 °C for 15 min, the slate alone heated rapidly, reaching 500 °C within 3 min on the side opposite to the flame. However, the sandwich structure reached 260 °C on the cork side (opposite to the flame) at 7.5 min, maintaining this temperature until the deterioration or detachment of the cork between 11 and 12 min. This provided insulation and delayed ignition. The sandwich structure maintained its fire resistance due to the insulating properties of cork and the superior thermal resistance of silicone compared to other adhesives up to 260 °C. Overall, the results suggest the potential suitability of this sandwich structure for architectural applications. Its favourable adhesion properties and acceptable fire resistance indicate that it could serve as a viable alternative for construction materials in architectural contexts.

Responsible Humidity Sensor by Direct Laser Writing on Cork Substrate

AbstractA novel laser‐induced graphene (LIG) resistive relative humidity (RH) sensor is successfully fabricated by direct laser writing on a common natural cork sheet. In this work, a straightforward fabrication is presented where LIG, porous multilayer graphene, is generated by a laser photothermal process on a carbon‐based substrate, in this case, an agglomerate cork sheet. The formation of LIG material is revealed by structural and morphological characterization using various analyses, including Raman spectroscopy, X‐ray Photoelectron spectroscopy (XPS), and Scanning Electron Microscopy (SEM). The electrical analyses are conducted to measure the resulting sheet resistance, getting results as low as 31 Ω sq−1. With the laser parameter optimized, a LIG resistive humidity transducer is manufactured and characterized in a climate chamber. This biodegradable sensor shows good linearity with a sensitivity of 0.015%/%RH from 40 to 80% RH. Additionally, the influence of temperature is studied and demonstrated a low impact on the sensor's response toward RH. Furthermore, a proof of concept is successfully implemented by integrating the transducer onto a cork stopper. Considering all, the prospect of creating an easy, fast, scalable, and cost‐effective transducer combined with the use of natural and abundant materials, leads the way for future large‐scale production of sustainable sensors.

Cork Sheet as an Efficient Biosorbent forForensic Toxicology: Application to Vitreous Humor Analysis.

There is an increasing number of people affected worldwide by mental health disorders, such as depression and anxiety. One of the main courses of treatment, along with psychotherapy, is the use of psychoactive medications, like antidepressants and benzodiazepines. Also, the unprescribed use of these substances is a concerning public health issue. Hence, the analysis of psychotropic medications is mandatory in postmortem toxicology and various biological samples can be used for this detection, among them the vitreous humor (VH) stands out. Also, there is a demand for more sustainable and more efficient extraction methodologies according to green chemistry. An example is solid phase microextraction techniques (SPME), which use a solid sorbent and small solvent amounts. Biosorbents are substances of natural origin with sorptive properties, and they have been successfully used in SPME in environmental toxicology for water analysis, mainly. This study aimed to develop a sustainable, fast, cheap and simple SPME methodology using cork sheet strips as a biosorbent, to extract antidepressants, benzodiazepines and others from VH samples by liquid chromatography coupled to tandem mass spectrometry. The extraction was conducted in a 96-well plate using 200 µL of VH and optimization of relevant parameters for extraction was performed. For solvent optimization, two simplex-centroid experiments were planned for extraction and desorption and to evaluate time and pH, a Doehlert design experiment was performed. The analytical method for the determination and quantification of 17 substances was validated. The quantification limits were 5 ng/mL for all analytes and the calibration curves were linear between 5 and 30 ng/mL. This study was able to develop an efficient, cheap, simple and fast microextraction method for 17 analytes in VH, using strips of cork sheet for extraction and a 96-well plate as a container. Furthermore, this approach system could be automated for routine toxicology laboratories.

Sustainable Laser‐Induced Graphene Electrochemical Sensors from Natural Cork for Sensitive Tyrosine Detection

AbstractCork laser induced graphene (cork‐LIG) electrochemical sensors are fabricated by direct laser writing of natural cork sheets. Laser writing is performed with a hobbyist visible laser. The obtained cork‐LIG structures display graphene‐like Raman signatures, high conductivity, and fast electron‐transfer rates. After a 10 min electrochemical pretreatment, electrodes are used for detection of Tyrosine (Tyr) in the presence of uric acid, dopamine, ascorbic acid, urea, and glucose. linear detection of tyrosine is achieved in the 5–150 µm range with a limit of detection (LOD) of 3.03 µm. Calibration of dopamine detection is achieved with a LOD of 1.1 µm. Finally, the cork‐LIG electrochemical sensors show linear response of Tyr in artificial sweat in the relevant physiological range of 5–250 μm (sensitivity, 1.8×10−2 A m−1). The LOD is calculated as 3.75 μm. These results open the door to the exploitation of renewable materials such as cork for the development of high‐quality, green sensors for the monitoring of health and wellbeing parameters.

Characteristics of fresh and frozen semen of Red Chittagong Cattle

Semen production from breeding bulls used in Artificial Insemination (AI) program is of great importance in cattle breeding. Good quality semen has positive effect on the fertility of cows and heifers. The aim of this study was to evaluate the quality and assessed as the freezing ability of Red Chittagong Cattle (RCC) bull with fresh-diluted semen and frozen semen. The parameters of semen characteristics included were volume per ejaculate (ml), percentage of mass motility, normal and abnormal sperm, and sperm concentration (million/ml). The highest mass motility was found in bull ID No. 4 and the lowest in bull ID No. 1 but the highest sperm concentration was found in bull ID No. 3 with lowest in bull ID No. 2 in fresh semen. Highly significant (p<0.001) positive correlation was found between mass motility and sperm concentration in bulls of ID No. 3 and 4, a negative significant (p<0.05) correlation was found between mass motility and normal sperm percentage. Two freezing techniques were followed in frozen semen production: Cork sheet freezing and Cryobath freezing with two freezing times 15 and 30 minutes were also applied. Variations in the motility of frozen semen by Cork sheet freezing with two different times were found significant (p<0.05) between bulls. Furthermore, highly significant (p<0.01) difference of motility by Cryobath freezing was found between the bulls. The highest motility after both 15 and 30 minutes Cork sheet freezing and Cryobath freezing was found in bull ID No. 4 and lowest in bull ID No. 3. In the present study, variability in the potentiality of bulls (semen volume and sperm concentration) was observed and found lower than crossbred bulls due to small size of Red Chittagong, an indigenous zebu cattle of Bangladesh. Bangladesh Journal of Animal Science. 51(1):25-30

Basic Studies Aiming at Orius minutus (Hemiptera: Anthocoridae) Mass-Rearing.

Simple SummaryThe rapid growth of the biocontrol market is increasing the research into the usefulness of native natural enemies. For the commercial use of native natural enemies, economical mass-rearing technology must be developed. This study was conducted to establish a mass-rearing technique for improving the usability of Orius minutus in Korea. This species uses plants for moisture intake, nutritional supplementation, and oviposition substrates. However, the use of plants in mass production systems significantly increases the cost of production. Eggs of stored grain insect pests used as food in rearing Orius spp., are the most nutritionally balanced food source, but their high market price necessitates the selection of an economical food source to replace them. In this study, Ephestia cautella eggs and iron-coated brine shrimp eggs were selected as diet, and cork sheets were selected as an artificial oviposition substrate to obtain basic data for establishing a plant-free rearing system. The plant-free model developed in our study can reduce rearing costs by 70.5% compared to the conventional mass-rearing model.This study presented biological and economic data for the mass-rearing of Orius minutus in Korea. Simplifying the mass-rearing process through an alternative diet and an artificial oviposition substrate is a prerequisite for enhancing the usability of this insect as a biological control agent. We compare the hatch rate of O. minutus eggs deposited on a plant substrate with that of eggs deposited on two artificial substrates, cork sheets and rubber. The results indicate that cork sheet is the most cost-effective artificial oviposition substrate for the mass-rearing of O. minutus. We also examine five feeding treatments that included two types of brine shrimp eggs and eggs of Ephestia cautella to compare the number of eggs laid in the fifth generation. We found no significant difference between the two treatment groups; 61.3 eggs were laid in the treatment group fed iron-coated brine shrimp and moth eggs, and 67.4 eggs were laid in the control group. The plant-free model developed in our study can reduce rearing costs by 70.5% compared to the conventional mass-rearing model.

Membrane-type acoustic metamaterial using cork sheets and attached masses based on reused materials

To contain the environmental impact of modern buildings it is necessary to design in a sustainable way, making efficient use of energy resources and raw materials. The reduction of waste requires a review of the policy of valorizing raw materials by resorting to recycling and reuse as much as possible. In this study, a new membrane-type acoustic metamaterial was developed using a recycled cork membrane and fixing to this membrane masses obtained by reusing thumbtacks and buttons. About 42 samples were packaged by attaching different combinations of masses to the cork membrane. The specimens thus obtained were used to measure the sound absorption coefficient by means of an impedance tube. To improve the acoustic properties of the material, the benefits of membrane resonance absorption and cavity resonance absorption were coupled, leaving a 50 mm cavity at the end of the tube. Subsequently, the measurements were used to train a regression tree-based sound absorption coefficient prediction model. The results obtained suggest using these structures for the acoustic correction of the rooms.

2-Piece Cork Stoppers as Alternative for Valorization of Thin Cork Planks: Analysis by LCA Methodology.

Natural stoppers are a magnificent closure for the production of aging wines and unique wines, whose application is limited by the availability of raw materials and more specifically of cork sheets of different thickness and quality. The growing demand for quality wine bottle closures leads to the search for alternative stopper production. The two-piece stopper is an alternative since it uses non-usable plates in a conventional way for the production of quality caps. The present study has analyzed the impact of the manufacture of these two-piece stoppers using different methodologies and for different dimensions by developing an LCA (Life Cycle Assessment), concluding that the process phases of the plate, its boiling, and its stabilization, are the phases with the greatest impact. Likewise, it is detected that the impacts in all phases are relatively similar (for one kg of net cork produced), although the volumetric difference between these stoppers represents a significant difference in impacts for each unit produced.

Oil Spill Cleanup Using Chemically Modified Natural Fibers: Trial for Practical Application

An oil spill was simulated in a basin connected to the sea, which presents inside the National Institute of Oceanography and Fisheries. Two available natural fibrous materials were used after modification as sorbent materials for the treatment of oil spills. Sorption capacities of LCLA and PFLA onto crude oil were preliminarily examined in the laboratory before applying in the field. An amount of LCLA and PFLA were wrapped in a polyester circular pad. Cylindrical-shaped acrylic vessels, with perforated sides, were fixed with cork sheets to keep them floating on the water surface. 1.1 mm thickness of light crude oil was spilled inside the acrylic vessels. LCLA and PFLA containing pads were then dipped into an oil layer floating on seawater. Pads were laid into the interface between oil and seawater for 30 min (one pad per vessel). Sorption capacities were measured as 11.0 and 9.8 as gram oil per gram of sorbent for LCLA and PFLA, respectively. These results were close to the sorption capacities produced in the laboratory using the same oil and sorbent materials indicating that the tested sorbents have a cheerful application in the real field.

Cork from Quercus suber L.: Forest certification system for sustainable management of cork oak forests

Cork is the outer bark of the cork oak (Quercus suber L.), it is a secondary protection structure of tree, and its chemical composition is different from that of other lignocellulosic materials, as wood, agricultural, or forestry wastes. The best cork sheets are used to manufacture natural cork stoppers, vital in the aging process of “great” wines. It is a Mediterranean species covering an overall area of 2,139,942 hectares; Portugal and Spain countries where it occupies a larger area. This paper was developed to assess the possibility of implementing a system of payment for ecosystem services and/or a certification of forest management for small stands of cork oak privately owned areas of less than 25 hectares. The process is leaded by the Regional Groups of Forest Certification and Chain of Custody, main regional institutions. The system used is the Programme for the Endorsement of Forest Certification (PEFC). As specified by the multifunctional forestry applied in these ecosystems, its main use is the production of natural cork stoppers for the quality aging wines. The cork oak forests are living representatives of sustainability and a driving force of sustainable development.

USE OF CORK SHEETS FOR ROOM ACOUSTIC CORRECTION

ABSTRACT Cork is a sustainable material and at the end of its useful life it can be disposed of into the environment without causing damage. This paper analyzes an acoustic correction system made of cork sheets mounted at an opportune distance from the walls inside a room. The cork sheets have a thickness equal to 1.5 mm. The sound absorption coefficients of the cork sheets were initially evaluated by mounting samples inside an impedance tube, then creating a back cavity at a suitable distance from a rigid wall. The distances considered were: 3, 5, 10 and 15 cm. A room used as an office with a volume of about 90 m3 and plastered walls was considered as a case-study. In this type of environment, suitable acoustic comfort conditions are required. The acoustic characteristics were analyzed through a virtual model with an architectural acoustics software in an empty room and then with the introduction of sound-absorbing cork sheets. Measurements of the acoustic characteristics of the empty room were taken and subsequently with the walls lined with cork panels mounted at a distance of 3.0 cm from the rigid rear wall. A configuration was analyzed, in line with what was carried out in the numerical model, covering a surface of 5m2 of the room. The results of the numerical simulations as well as the experimental measurements are discussed.

Cork sheet as a sorptive phase to extract hormones from water by rotating-disk sorptive extraction (RDSE)

This work reports for the first time the use of laminar cork as a sorptive phase in a microextraction technique, rotating-disk sorptive extraction (RDSE). Typical hormones (estrone, estradiol, estriol and ethinyl estradiol) were selected as analyte models and extracted from wastewater samples on laminar cork with statistically equivalent extraction efficiency to that provided by Oasis HLB. The cork characterization was performed by confocal fluorescence microscopy (CLSM), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), allowing the identification of lignin, suberin and polysaccharides (cellulose and hemicellulose) as the main components of the cork. The best conditions for extraction were as follows: rotation velocity of the disk, 2000 rpm; extraction time, 45 min; and sample volume, 20 mL. The analytical features of the developed method show that calibration curves for all analytes have R2 values higher than 0.99. The absolute recoveries were higher than 63%, and the precision, expressed as relative standard deviation, ranged from 2 to 16%. The LOD and LOQ ranges were 3–19 and 10–62 ng L−1, respectively. The proposed method was applied to the analysis of wastewater, and the concentrations of hormones in a wastewater treatment plant in Santiago, Chile, ranged from <LOQ to 48 ng L−1.

Thermal Performance Evaluation of Cork Phenolic for Nozzle External Thermal Protection System Using 250 kW Plasma Jet Facility

In one of the launch vehicles of ISRO, there are two solid strap-ons attached to the core liquid engine. During the ascent phase, the external nozzle divergent of the strap-ons experiences heating due to radiation from the strap-ons as well as convective heating from the impingement of plumes from the core engine. Hence, the nozzle divergent of the strap-on beyond compliance ring is thermally protected by a coating of PC10 insulation applied over carbon/epoxy structural backup. Though the system worked satisfactorily, application of PC10 had increased the inert weight of each nozzle by 165 kg and took long time for realization. To reduce the inert weight as well as the time of application, precast phenolic based cork sheets (CkP) having lower density than PC10 were selected, as a replacement to PC10. As part of evaluating the thermal performance of the CkP material, specimen level tests with different configurations were carried out in 250 kW plasma jet facility of Vikram Sarabhai Space Centre (VSSC) wherein both the heat flux and the shear stress as expected in flight were simulated simultaneously. At the end of the test program, CkP was found to be superior to PC10 for external thermal protection system (TPS). This paper highlights details of the qualification tests carried out for clearing the cork phenolic system for use in the future launches.

Acoustic Properties of Cork Sheets

Green materials can be considered as a valid alternative to traditional synthetic materials. The cork is a green material, in fact it is a sustainable material. Cork can be used to improve the acoustics inside buildings. The systems used consist of cork sheets mounted at a distance onto a rigid wall, with the thickness of the sheet being 1.5 mm. The distances from the rigid wall considered are equal to 5 cm, 10 cm and 15 cm. The absorption coefficient of the sample was measured in the frequency range from 100 Hz to 2000 Hz with an impedance tube.

Dosimetric Accuracy Using the New Mathematical Tools for Inhomogeneous Denser Medium

It is possible to obtain a quality assurance (QA) of the dosimetry within a short time by using the new mathematical tools for a water phantom where dose measurements were made at two points only for a few square field sizes of the linear accelerator beam. The human body is not homogeneous. Water phantom makes it possible to create inhomogeneous phantoms by introducing blocks within it at suitable position to simulate body organs that may affect the dosage significantly. Two low cost inhomogeneous phantoms were developed using cork sheets and acrylic blocks to simulate the effects of normal lungs and cancerous lungs respectively using finite geometry and layer geometry. Monte Carlo Simulation was performed for each of these phantoms and detailed vertical and horizontal dose measurements were carried out. Percentage Depth Dose (PDD) measurements performed for the two point formalisms fixed at 100 cm Source to Surface Distance for both the homogeneous and inhomogeneous mediums and were compared with the doses generated by a Treatment Planning System. The quality of the methodology has ascertained firstly for a homogeneous medium. The formulated formalism of Tissue phantom ratio (TPR) was employed for inhomogeneous media particularly for finite and layer geometry using scattering factors obtained initially from detailed depth dose measurements. TPR conversion factors from homogeneous to inhomogeneous geometry were determined. The scattering factor was determined as a ratio of the depth dose in inhomogeneous medium and homogeneous medium. The quality factors of TPR values of homogeneous to inhomogeneous TPR conversion factor were also calculated. For all cases, the present results gave values which agreed very well to either actually measured values or with values calculated using TPS and these were also less than the international standard of deviation of 5%. The low cost inhomogeneous phantoms through modifications of the water phantom deliver better information on QA consuming less time than before and offering better QA than a detector array. The present work will have an impact on the quality assurance of dosimetry and safety of radiotherapy.

Indentation experiments on novel sandwich composite tubes

This article introduces a novel energy absorber of sandwich tube with the agglomerated cork core and the composite tube during the indentation process under the applied quasi-static lateral loading by a solid cylindrical rigid indenter. Also, the corresponding cork specimens and the empty composite tubes are tested, too. The solid cylindrical cores made of agglomerated cork are prepared by punching a cork sheet with 200kg/m3 density and positioned into the composite tubes to manufacture the cork-filled tubes. The results show that the cork-filled composite tubes have an energy absorption capacity up to 5.65 times of the corresponding cork sample and up to 6.06 times of the corresponding empty tube. Also, it is found that total absorbed energy by a cork-filled composite tube is 174% higher than summation of absorbed energy by the corresponding empty tube and the cork sample. Also, specific absorbed energy by all the specimens is discussed.

CorkSTFμfluidics – A novel concept for the development of eco-friendly light-weight energy absorbing composites

CorkSTFμfluidics are environmentally friendly composites consisting of a laminar sheet of compacted micro-agglomerated cork engraved with a network of microchannels by laser and filled with a concentrated aqueous solution of cornstarch (shear thickening fluid). Thus the mechanical properties of these composites will result from the combination of the mechanical properties of the micro-agglomerated of cork and the enhanced shear thickening response of the STF flowing through the network of microchannels. In this work we have performed low velocity impact tests using a drop weight testing machine in order to asses the improvement of these composites with regards to the micro-agglomerated of cork alone. A numerical analysis was also performed and allowed to understand how shear thickening behavior is triggered by the appropriate combination microchannels’ size and the inlet velocity. Thus, for the 60P/40S/M sample, the peak force was larger than the one given by the cork sheets without engraved microchannel nor STF.

Thorn-Shape Waveform and Double-Strike Phenomenon Seen in the Impact Force of Soft Materials

In the impact tests of soft materials, we sometimes observe a thorn shape in the rising segment of the impact force waveform. However, the reason for the occurrence of the thorn shape has not been made clear. In this study, thorn-shape waveforms of several soft materials are measured using compact drop test equipment under the condition of a flat frontal impact. A flat frontal impact is the condition where a drop hammer with a flat bottom surface strikes a plate-like soft material in the normal direction. Synchronized impact forces are measured using two sensors installed on both the drop hammer side and the floor side. The examined soft materials are a sponge sheet, sponge rubber sheet, gel sheet, rubber sheet, flat oil clay, low-rebound urethane foam, cork sheet, sliced ham, pork ham steak, and pork. Based on the test results, the features of the thorn-shape waveforms are discussed from a bird’s-eye view. Furthermore, the occurrence mechanism of the thorn-shape waveforms is discussed from the viewpoint of viscosity discontinuity and the double-strike phenomenon.

Effect of surface treatments on natural cork: surface energy, adhesion, and acoustic insulation

Cork is one of the finest natural materials with high acoustic insulation properties due to its porous structure. In addition, cork presents high water resistance due to its hydrophobic nature. In many applications, cork panels need to be bonded to other materials for manufacturing composite materials or agglomerated cork sheets. In this case, its lack of wettability becomes an important disadvantage. This paper aims to improve the wettability of cork by silanization, atmospheric plasma treatment, and vacuum plasma treatment. The processing conditions of the three treatments were optimized. The surface characterization was performed by surface energy, roughness, and attenuated total reflectance-Fourier transform infrared spectroscopy measurements. Pull-off adherence and peel tests were carried out to evaluate the performance of the treatments with an epoxy adhesive. Plasma treatment of cork plates could be a useful tool to enhance adhesion properties in the manufacturing process of cork sandwich panels or other applications where it could be joined to any material.

TH-D-AUD B-06: Variability of Low-Z Inhomogeneity Correction in IMRT/SBRT: A Multi-Institutional Collaborative Study

Purpose: The dosimetry of IMRT beamlets with low-Z inhomogeneities is a difficult problem and its accuracy is highly uncertain due to lateral disequilibrium. Various inhomogeneity correction algorithms: pencil beam (PB), collapsed cone convolution (CC), anisotropic analytical algorithm (AAA), Monte Carlo (MC), and combination of them are employed in different treatment planning systems (TPS) for dose calculations. This multi-center collaborative study evaluates the accuracy and suitability of these algorithms for inhomogeneity correction in clinical trails. Method and Materials: A simple lung phantom was constructed with cork sheets (0.25 g/cm3) sandwiched between two 3 cm thick solid water slabs. The CT data of this phantom was sent to 8 institutions employing different TPS. Dose calculations were carried out at various depths over the field sizes: 0.5×0.5–10×10 cm2 for 6 and 15 MV beams with grid size (2×2 mm2). The calculated inhomogeneity correction factor (CF) was compared with measured data using a micro-chamber. Results: The calculated CF with various algorithms showed marked variability and can be categorized in two classes; pencil beam (PB) and MC based collapsed cone (CC). The CF calculated with PB rises steadily in the lung tissue whereas CC exhibits the effect of electron transport. The differences between measured and calculated CF values varied from 70% to −10% for 6 MV from small to large fields. For 15 MV beam, the differences are even larger for small fields but reduce significantly for large field sizes (>5×5cm2). Conclusion: It is concluded that PB based algorithms should be avoided for dose calculation in small fields with low-Z inhomogeneities. The MC derived kernel based algorithms such as CC and AAA produce similar results to each other within ±10% and should be preferred for patient treatment in IMRT/SBRT. This study raises serious concerns in dosimetric variability in lung cancers possibly impacting the clinical trials.