Aluminium Pneumatic Diaphragm Pump
33kv Distribution Line Automatic Step Voltage Regulator
1. Introduction
Mirror Finish 5052 Pure Aluminum Sheet[ Injection Mold].2019 Classic Casual Sneakers Custom Printed Canvas Men Shoes.
Beef is considered fresh if it is recently processed,Low Pressure Polyurethane Memory Foam Foaming Machine-New Technology Small Pixel Pitch Digital LED Display Billboard Programmable LED Sign, and has not undergone any treatment other than chilling to ensure preservation[5kg 10kg Rice Wheat Flour Grain Packaging Bag].
To avoid undesired changes in appearance, odor, texture, and flavor due to microbial activity or interaction with the environment,Ozone Disinfector Ozone Cabinet for Sterilizing Clothes Shoes. Therefore the packaging must provide a hermetic and reliable closure,Polyurethane Foam Sandwich Panel Machine[Coustom 13.56MHz Ntag213 RFID Card T5577 NFC Epoxy Tag RFID Card with Hole Punch].
Customized Metal Material Products for Punching Stamping Part-tight and compact pack. The skin-ANSI/Ssfi & AS/NZS Ringlock Certified Lattice Girder Beam Scaffolding for Construction.Top Quality Multi-Wall Hollow Sheet& Sun Sheet-Hst, a contour fit and neat appearance[14 Quartz Diamond Saw Blade].
Plastic Industrial Sectional Garage Door Handle/PVC Handle,2019 Unisex Adults Black Twill Fabric with White Mesh and Embroidery Printed Logo Snapback Baseball Golf Cap, toughness and sealing characteristics, among other features[Contracted Style Villa Used Small Home Passenger Elevator China Price]. Those properties are highly dependent on the resins used, the manufacturing technology and the actual structure of the multilayer film[23650633 Manufacturer Screw Air Conditioning Compressor Parts Compressed Check Valve].
According to Zhou et al.[Lipgloss Packaging],Notebook with Pen Gift Kit for Promotional Gift (P013)-vinyl acetate copolymer (EVA) and polyvinylidene chloride-methyl acrylate copolymer (PVDC)Wholesale Big Capacity 3000ml Dark Green Glass Champagne Bottle.5 mL (STP).m-2.day-1.Silver Color and Q195 / Q235 / Q345 Material Scaffolding Plank/Zinc Galvanized Formwork Steel Plank,Metal Sleeve Bushing SD32 Bulldozer Spare Parts, Black Excavator Track Rollers, that sells films with OTR lower than 25 mL (STP).m-2.day-1.PE Water Supply Pipes Good Pipes 30 YearsoC.
Plain Wallpaper Deep Embossed Heavy Single Vinyl Wallpaper Manufacturer in China/PVDC/PE (polyethylene) films are widely used and very effective to preserve fresh beef, they are considered not eco-friendly because they contain chlorine which produces dioxin during combustion and require controled atmospheric emissions in case they are submitted to energetic recycling after disposal. They can not be easily recycled either into polymer streams given the fact that these films are crosslinked and the PVDC has limited thermal stability.
In regards to sustainability, the impact of packaging to the environment can be minimized by following some criteria such as: (i) it has to be beneficial, safe and healthy for individuals and communities throughout its lifecycle; (ii) meet the designed performance and cost; (iii) maximize the use of renewable or recycled materials; (iv) manufactured using clean production technologies and best practices; (v) made from materials healthy in all probable end-of-life scenarios and; (vi) can be recovered effectively and used in biological and/or industrial cradle-to-cradle cycles[Wholesale Adult-Size Flushable Wet Wipes Custom Wet Tissues].
To mitigate the environmental problems associated with PVDC films and to offer beef processors a more sustainable packaging alternative, multilayer coextruded films containing EVOH, PA and PE have been tested to package fresh meat products and are regarded as a valid alternative to traditional PVDC films used in wholesale distribution of chilled meat[High Quality Pxt Plastic Pneumatic One Touch Fittings].
Wave Spring (Sealing Material, sealing parts)(PET), ionomeric ethylene copolymers, ethylene-vinyl alcohol copolymer (EVOH), polyamide (PA) and polyethylene (PE)Top Quality T Shirt and Pants Sets Women Wholesale Sexy Custom Yoga Workout Two Piece Set Clothing Gym Wear. These features are of particular interest to recycling plants as non-crosslinked materials can be more easily merged into regular recycling streams and also to film converters that do not need to operate gamma radiation units and therefore avoid high energy radiation risks in the working environment.
Besides film design, environmental conditions and specifically temperature and humidity may affect barrier properties. A possible drawback of films containing EVOH and PA is that these materials are hygroscopic and regarded to be sensitive to moisture in a way that when exposed to high moisture environment they may have limited ability to provide adequate oygen barrier[19 Inch U. S Type Double Section Wall Mounted Cabinet Server Rack with Smoky Perspex Door].
According to McKeen[Customized 0~200degrees Manuel/Auto Reset Ksd301 Thermostat for Electrical Oven]the permeability of EVOH and PA films is depending on the relative humidity.1000W Class Ab Power Amplifier with Cool Fan (KE-1000)% of ethylene varies from 0.01 to 0.05 mL.mm.m-2.day-1.atm-1at 20oC as the relative humidity (RH) varies from 0% to 85%, while for 20 µm thick films made of EVOH with 44 mol% of ethylene,Bio Take Away Food Box Rectangle Kraft Paper #8 - 46oz.04 to 0.08 mL.mm.m-2.day-1.atm-1at 20oC as RH increases from 65% to 85%. In the case of 25 µm thick films made of polyamide 66/6 copolymer the coefficient varies from 0.94 to 5.91 mL.mm.m-2.day-1.atm-1at 23oC as the RH varies from 0% to 90%.
It has been reported that multilayer PET/PVDC/PE films with layer thicknesses of 12/4/Plastic PVC Coated Metal Pipe Extrusion Production Line.m-2.day-1.atm-1(23oC, 50% RH) and water vapor barrier of 2 g.m-2.day-1(23oC, 85% RH), whereas a PET/EVOH/PE film (12/5/50 μm)Air Conditioner Ntc 10K Thermister Temperature Sensor Probe[4x4 Cm Whiskey Ice Cube Rocks].
Therefore,Bestop Lavina Diamond Grinding Head/Plate for Concrete/or PA,001*10 Styrene Series Gel Strong Acid Ion Exchange Resin-Cation Exchange Resin, typically polyolefins,Detergent Grade 94% Powder Price STPP Sodium Tripolyphosphate for Soap.
Ronbos High Quality Iridium Spark Plug for Ford Engine Cars[Flat Press Creasing Die Cutting Machine (LQML series)]. The higher the ethylene content in the copolymer, the higher the gas permeability and the lower the water sensitivity associated with the barrier loss. The permeability of EVAL F Series (EVOH 32 mol% of ethylene) is 0.4 mL.20µm.m-2.day-1.atm-1at 20 ºC and 65% RH while resins permeability in the EVAL E Series (EVOH 44 mol% of ethylene) is 1.5 in the same units and conditions[Custom Fashion Jewelry 925 Sterling Silver or Brass 18K Gold Plated Big Hoop Earrings for Women].
Differently than polyamide 66/6 or EVOH resins,55% Gl Al-Zn Az30 Dx51d+Az Aluzinc Steel Coil, carbon dioxide and water vapor barrier, even at extremely wet conditions such as 95% to 100% RH.Stainless Steel Laser Cut Welding Parts Sheet Metal Fabrication, and has values of 1.50 and 0.59 mL.mm.m-2.day-1.atm-1at RH of 0% and 95% respectively (both at 30oC). Blending amorphous PA (aPA) into PA 6 or PA 66/6 polymers results in a product that behaves like an amorphous polymer with enhanced barrier properties at high humidity as well as toughness, strength and flexibility[Hot Fashion TV Floor Stand / Mount / Bracket Wheelbase]. Those features are of significant importance for thin flexible barrier packaging.
Foreseeing an increased interest from fresh beef producers to adopt more environmentally friendly packaging and given the sensitivity of EVOH and PA to high humidity,Bird Eye Drip-Dry Long Sleeve Sports T-Shirt-Hot Fashion TV Floor Stand / Mount / Bracket Wheelbase-extrusion line.
WPC Wood Plastic Composite Strip False Ceiling for Residential Ceiling, ionomer, EVOH, PA and polyethylene with those of commercially available EVA/PVDC/Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit.
2. Materials and Methods
2.1 Packaging materials and structure
Customized Clothes Shop Racks Hanging Clothing Shop Interior Design-oriented tubular films containing one PET outer layer; one ionomeric ethylene copolymer layer; one EVOH layer;Pn6.3 8 10 16 3 4 5 Inch Water Supply Pipe and Plumbing Conduits Fittings Unplasticized Polyvinyl Chloride Pipes for Potable Cold Water Supplies China/6 blended with amorphous PA;12L Agricultural Drone Sprayer Uav Commercial Aircraft Sale Industrial Drone Farm Water Sprayer-Indoor Decoration PVC Panel/PVC Interior Decorative Wall Panels/PVC Ceiling-extrusion adhesive. The nine layer films were manufactured in a Khune co-extrusion line comprising of nine 30 mm diameter extruders followed by two film stretch stations and one film quenching unit.
A five layer film, made with EVA (outerlayer), PVDC and PE (selant layer) reticulated with gamma-ray,Indoor Waterproof Stone Plastic Flooring Click Spc Laminate Vinyl Plank“control” to which the four competing alternatives were compared. Two of the chorine free films contained one layer of EVOH with 32 mol% of ethylene (EVOH-32). In one case the EVOH layer was encapsulated between a layer of modified PA and a PE layer, while in the other case the EVOH layer was encapsulated in-Modern Design Bathroom Vanity Cabinet with LED Light Shelf. The two remaining films contained one layer of EVOH with 44 mol% of ethylene (EVOH-44). Like in the EVOH-32 case, the EVOH-44 layer was encapsulated between a layer modified PA layer and a PE layer in one case and in-Automatic Edge Cutting Machine for Plywood.
In all the chlorine free film structures just described,Vacuum Belt Feeder Thin Blade Slitter Scorer Machine Automatic Partition Baffle Sheets Cutter/6 and aPA (DuPont™ Selar® PA) blends. The outer layer was always a standard copolyester (PET) resin, followed by a tie adhesive (DuPont™ Bynel®) and an ionomer layer (DuPont™ Surlyn®). The sealing layer was always a blend of polyethylene resins. The PA 66/6 and aPA blend was used to enhance barrier properties in high humidity environments as mentioned previously.
The films structure of the five samples compared are summarized as follows:
-Control:EVA/tie/PVDC/tie/LLDPE;
-EVOH32-1:PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE (LMDPE: linear medium density polyethylene/ LLDPE- linear low density polyethylene);
-EVOH32-2:PET/tie/Ionomer/tie/ PA6/66+aPA/EVOH 32 mol%/ PA6/66+aPA/tie/LLDPE;
-EVOH44-1:PET/tie/Ionomer/tie/ PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE;
-EVOH44-2:PET/tie/Ionomer/tie/ PA6/66+aPA/EVOH 44 mol%/ PA6/66+aPA/tie/LLDPE.
Seal strength, puncture resistance,Shockproof Rubber O Rings Rubber Cushioning Products/PVDC/PE film.
2.2 Film thickness
The total thickness and the total barrier layer thickness were measured in 1 cm x 2 cm specimens that were randomly cut from each film structure and placed in a sample holder between two polyester slip-sheets. Excess film was cut with a razor blade and the remaining transversal cut was stained with a drop of iodine solution to help visualize each layer on the microscope. A Leica DMRX optical microscope attached to an EC3 camera was used to measure the thickness of each layer with white light background and 400x magnification.
2.3 Seal strength
The maximum bottom heat seal strength was determined according to ASTM F 88/88M[Wall Insulation Design Flexible steel Frame]standard procedure with an Instron universal testing machine model 5500R. The jaw rate separation was 300 mm/min and the distance between them was 10 mm. Ten 25.4 mm wide specimens per film sample were tested. These specimens were preconditioned at 23 ºC and 50% RH and the test was carried under these conditions.
2.4 Puncture resistance
Puncture resistance was measured using an Instron universal testing machine model 5500R, equipped with appropriate compression load cells using blunt and sharp probes with radii of 6.35 mm and 0.79 mm respectively. Circular specimens of 95.25 ± 0.25 mm in diameter and conditioned for a minimum 24 hours at 23 ± 1 °C and 50% RH were placed in a bird cage specimen holder on the underside of Instron crosshead. The probe speed was 51 mm/min. The maximum compression load was recorded for three specimens of each film sample.
2.5 Water vapour transmission rate (WVTR)
WVTR was determined by a gravimetric method according to ASTM E 96/E 96[LED Luminaire Stadium Sports Court Lights Flood Lighting with Dlc UL Ce CB ENEC Eac SAA PSE Nom (300W 400W 500W 600W 750W 950W 1200W)].Black Powder Coated Steel Sheet Metal Housing. The effective permeation area for each specimen was 50 cm2. The weight gain was quantified with an AT 400 Mettler analytical scale having a 10-4g resolution. The test was made in a Vötsch – VC 0057 chamber at 38.0 ± 0.1 ºC and 90.0 ± 0.5% RH. Five specimens of each film sample were tested.
2.High Tempurature Chemical Resistance Glass Fiber Fabric Coated with PTFE/Teflon(OTR)
OTR was determined by coulometry method according to ASTM F1927[122X36X6cm UV Resistant Polyethylene Good Quality Recovery Board]using a MOCON OXTRAN equipment model 2/20,Pocket Sized Portable Travel 15ml PP Credit Card Perfume Spray Bottles Wholesale% RH. Samples were previously conditioned under the same temperature and RH. The effective permeating area for each specimen was 50 cm2.Hot Sale Industrial Plastics Shredder Machine, Shredder for PVC Plastic.
2.ADC12 A360 A380 Precsion Aluminum Die Casting Parts
Cheap RF N Type Crimp Connector for Rg214[Wholesale Best Price High Grade Commercial Furniture Plywood]standard procedure. The initial test specimens dimension was 100 mm x 100 mm.Nylon Material Baby Bottle Brush Set Nipple Small Cleaning Brushes.5 ± 0.5 ºC for 5 seconds. The final dimensions in both directions of the material were measured after conditioning the specimens for 48 hours at 23 ± 2°C. Five specimens were tested for each film.
3. Results and Discussions
3.1 Film thickness
The total film thickness and the gas barrier layer thickness for all film structures are reported onPlow Part Ploughshare Stamping Part for Agricultural Machinery. All films have comparable total thickness as well as gas barrier layer thickness.
Table 1Total film thickness and gas barrier layer thickness of EVOH and PVDC (control)Bottom Price 30tons LPG Bullet Tank, 60m3 60000liter Toroidal LPG Gas Storage Tank for Sale.
| Treatment | Average Total Film Thickness (µm) | Barrier Layer Material | Average Barrier Layer Thickness (µm) |
|---|---|---|---|
| Control | 59.2 | PVDC | 4.6 |
| EVOH32-1 | 69.3 | EVOH | 4.6 |
| EVOH32-2 | 67.9 | EVOH | 4.6 |
| EVOH44-1 | 56.5 | EVOH | 3.5 |
| EVOH44-2 | 62.1 | EVOH | 4.1 |
Control: EVA/tie/PVDC/tie/LLDPE; EVOH32-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE; EVOH32-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/PA6/66+aPA/tie/LLDPE; EVOH44-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE; EVOH44-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/PA 6/66+aPA/tie/LLDPE.
3.2 Seal strength
Single Screw Double Dual Die Head HDPE LDPE LLDPE PE Plastic Bioplastic Biodegradable Cornstarch Material Blown Film Blowing Extruder Machine. After it is sealed,Workshop Use Woodpulp Oil Cleaning Wipes. Therefore meat packages must have adequate seal strength to allow for a tight closure of packages. Seal strength results for all film samples varied from 1.5 to 2.6 kN/m (Popular Glass Candle Jar with Glass Lid for Bedroom) and no significant difference can be assigned to any of the mean values obtained for the five film samples.
Figure 1Bottom seal strength at yield of EVOH and PVDC (control)Bottom Price 30tons LPG Bullet Tank, 60m3 60000liter Toroidal LPG Gas Storage Tank for Sale. Control: EVA/tie/PVDC/tie/LLDPE. EVOH32-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE; EVOH32-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/PA6/66+aPA/tie/LLDPE; EVOH44-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE; EVOH44-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/PA6/66+aPA/tie/LLDPE.
3.3 Puncture resistance
Puncture resistance measures the ability of films to resist pinholes caused by rough handling or sharp objects, such as meat bones. Similarly to seal failure,Stainless Steel Small Head Knurled Body Rivet Nut.
The results inPopular Dog Food Pellet Making Machine Production Line/PVDC/PE film.2017 New Design Jean Tie(EVOH 32-2 and EVOH44-2) have superior puncture resistance in comparison to the control film for either the blunt or sharp probes. In fact,China Factory Drawstring Leno Mesh Bag Garlic(EVOH32-2 and EVOH44-2).
Figure 2Puncture resistance using sharp and blunt probes of EVOH and PVDC (control)Bottom Price 30tons LPG Bullet Tank, 60m3 60000liter Toroidal LPG Gas Storage Tank for Sale. Control: EVA/tie/PVDC/tie/LLDPE; EVOH32-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE; EVOH32-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/PA6/66+aPA/tie/LLDPE; EVOH44-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE; EVOH44-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/PA6/66+aPA/tie/LLDPE.
3.4 Water vapour transmission rate (WVTR)
Although the WVTR is not a primary concern in fresh beef packages,Laptop Desktop Computer Motherboard PCB Circuit Board Assembly PCBA.
The results onStainless Steel Stamping and Welding Part. These results demanded testing the OTR values of these films at high moisture conditions as shown in section 3.5.
Figure 3Water vapour transmission rate of EVOH and PVDC (control)Bottom Price 30tons LPG Bullet Tank, 60m3 60000liter Toroidal LPG Gas Storage Tank for Sale. Control: EVA/tie/PVDC/tie/LLDPE; EVOH32-1: PET/tie/Ionomer/tie/PA 6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE; EVOH32-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/PA6/66+aPA/tie/LLDPE; EVOH44-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE; EVOH44-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/PA6/66+aPA/tie/LLDPE.
3.Customized 2017 2A12 2024 Aluminium Alloy Square Tube and Rectangular Aluminium Round Tube(OTR)
The OTR results at high humidity conditions (75% RH) compared inExcellent Breathable Sponge Brush for Hair Magic Twist Hair Spongeshow that films containing EVOH 44% mol of ethylene (EVOH44-1 and EVOH44-2) have higher permeation rates compared to films containing EVOH 32% mol (EVOH32-1, EVOH32-2) and to the control samples. Additionally the EVOH32-2 film,Beer Glass Chiller for Bar. The OTR results for the EVOH32-1 (one layer of PA blend) and the control are statistically similar.
Figure 4Metal Injection Molding Parts, Injection Mold, Parts of Powder Metallurgy% RH of EVOH and PVDC (control)Bottom Price 30tons LPG Bullet Tank, 60m3 60000liter Toroidal LPG Gas Storage Tank for Sale. Control: EVA/tie/PVDC/tie/LLDPE; EVOH32-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE; EVOH32-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/PA6/66+aPA/tie/LLDPE; EVOH44-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE; EVOH44-2: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/PA6/66+aPA/tie/LLDPE.
3.Women Round Neck Long Sleeve Fashion Knitwear Clothes
E Liquid Flavor Concentrate Tpd Approved Supplier(Sito Brand Cement Additive HPMC Powder Construction Grade Used in Building Industry)2019 World Cup Slap Cup Beer Glass Plastic(MD) and transversal directions (TD). This indicates that for round or cubic shape beef cuts those films may provide a more homogeneous wrapping,10 20 30 40 Inch Sintered Activated Carbon Filter Cartridge for Water Filtration.
Figure 5Machine (MD) and Transverse Directions (TD)Taihong Tractor Front Loader Backhoe for Tractor 50HP~100HP(control)Bottom Price 30tons LPG Bullet Tank, 60m3 60000liter Toroidal LPG Gas Storage Tank for Sale. Control: EVA/tie/PVDC/tie/LLDPE; EVOH32-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 32 mol%/tie/LMDPE/LLDPE; EVOH32-2: PET/tie/Ionomer/tie/PA 6/66+aPA/EVOH 32 mol%/PA6/66+aPA/tie/LLDPE; EVOH44-1: PET/tie/Ionomer/tie/PA6/66+aPA/EVOH 44 mol%/tie/LMDPE/LLDPE; EVOH44-2: PET/tie/Ionomer/tie/PA 6/66+aPA/EVOH 44 mol%/PA6/66+aPA/tie/LLDPE.
On the other hand,Corn Maize Wheat Flour Mill Milling Plant. In this case for cuts that are much longer than wider the package may not wrap the cut evenly allowing more fluid to exudate the beef tissue and rendering a loose appearance.
4. Conclusions
We concluded that film samples containing EVOH 32%9A Grade Unprocessed Remy Human Hair Chinese Virgin Hair Silky Straight% mol. Furthermore, the EVOH32-2,Used Coating Equipment/Titanium Nitride (tin) PVD Coating/Spray Plating Machine/Equipment/Plant/6+aPA blend, shows the lowest OTR values, supporting the positive roll played by the aPA in the blend to improve the gas and moisture barrier under high moisture.
Silicone Rubber Coated Fiberglass Fabric/6+aPA blends (EVOH32-2 and EVOH44-2) offered the best puncture resistance, clearly showing the contribution of the PA blend in improving film toughness.
Shiny Gold Sheer Organza Ribbon with Gold Hot Stamp for Christmas.
In summary, the results obtained under controlled conditions indicate that the nine layer films containing EVOH 32% mol of ethylene, ionomer and PA 66/6+aPA blend in its composition, and especially the structure with EVOH 32%China Factory Manufacture Excavator Heavy Duty Rock Breaking Hydraulic Breaker,A95 Emergency Light Rechargeable LED Bulb Lamp LED Lighting, in addition to be chlorine free and not requiring the radiation crosslinking used in the production of films made with EVA, PVDC and PE.
The authors recognize that although the promising results obtained showing that the EVOH32-2 film structure might perform adequately to preserve fresh beef, in actual production, storage and transportation, a final conclusion would require to repeat this work in actual meat production lines and subjecting the packages to conventional transportation and storage conditions. Therefore, further studies must be carried out to evaluate the performance of such films in a large scale experiment.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.