EPS
Extracellular polymeric substances (EPS) are high-molecular-weight biopolymers secreted by microorganisms, consisting primarily of polysaccharides, proteins, lipids, and nucleic acids, which form a gel-like matrix that embeds and protects microbial cells in biofilms and aggregates.[1][2] These substances, representing metabolic byproducts and cell lysis remnants, enable microbial adhesion to surfaces, resistance to desiccation, antibiotics, and predators, while also trapping nutrients and facilitating horizontal gene transfer within communities.[3][4] In environmental and industrial contexts, EPS dominate the composition of activated sludge in wastewater treatment systems, comprising up to 90% of the dry mass and influencing floc stability, settling, and pollutant removal efficiency through their viscoelastic properties and binding affinities.[5][6] Their extraction and characterization remain method-dependent, with loosely bound and tightly bound fractions exhibiting distinct roles in microbial resilience and biogeochemical cycling, underscoring EPS as a key mediator of microbial ecology from soil interfaces to engineered bioreactors.[7][8]Finance
Earnings per share
Earnings per share (EPS) measures the net profit of a company attributable to each outstanding share of its common stock, serving as a primary indicator of per-share profitability.[9] Under U.S. GAAP and IFRS, basic EPS is calculated as net income minus preferred dividends, divided by the weighted-average number of common shares outstanding during the period.[10] [11] This formula assumes no changes in share count beyond actual issuances or repurchases, providing a straightforward view of earnings distribution among existing shareholders.[12] Diluted EPS expands on basic EPS by incorporating the potential dilutive effects of convertible securities, stock options, and warrants, which could increase the share count if exercised or converted.[13] The calculation adjusts the denominator using the treasury stock method for options or the if-converted method for debt and preferred stock, yielding a lower per-share figure that reflects worst-case dilution scenarios.[9] For example, if a company reports $100 million in net income, $10 million in preferred dividends, 50 million basic shares outstanding, and potential dilution adding 5 million shares, basic EPS would be $1.80 while diluted EPS might fall to $1.72.[13] Public companies must disclose both basic and diluted EPS on income statements per SEC requirements and standards like IAS 33.[11] EPS is central to financial analysis, enabling comparisons of profitability across firms and informing valuation multiples like the price-to-earnings (P/E) ratio, where stock price divided by EPS gauges relative affordability.[12] Investors use it to evaluate operational efficiency and predict dividend potential, as higher EPS often correlates with stronger cash generation for shareholders.[9] However, EPS has limitations: it can be inflated through share buybacks that reduce the denominator without improving underlying profits, or manipulated via accounting choices like revenue recognition timing.[14] It ignores capital structure, cash flows, and non-operating items, potentially misleading assessments of long-term sustainability, and is less meaningful for unprofitable firms with negative values.[15] Analysts thus pair EPS with metrics like free cash flow per share for a fuller picture.[12]Computing and graphics
Encapsulated PostScript
Encapsulated PostScript (EPS) is a standardized file format for vector graphics that encapsulates PostScript code conforming to Document Structuring Conventions (DSC), enabling the representation of a single graphic or page element suitable for embedding in other documents or for high-resolution printing.[16] Developed by Adobe Systems, EPS files primarily contain textual PostScript instructions for rendering scalable images, alongside support for embedded bitmap data, making them versatile for professional graphic design and prepress workflows.[17] The format's design emphasizes device independence, allowing output on PostScript-compatible printers or imagesetters while preserving resolution and color fidelity.[18] Adobe introduced EPS in the late 1980s to facilitate the exchange and inclusion of graphics in text-based layouts, with the first formal specification emerging around 1987 and version 3.0 released in 1990, fully documented in a 1992 technical note.[16][17] This version, known as EPSF-3.0, mandates conformance to DSC 3.0 and restricts content to a single page without operators likeshowpage or exitserver that could disrupt embedding.[18] No subsequent versions have been developed, reflecting the format's maturity amid the rise of alternatives like PDF, though EPS remains in use for legacy printing needs such as signage, engraving, and scientific illustrations.[17]
Structurally, an EPS file is a plain-text document starting with a header such as %!PS-Adobe-3.0 EPSF-3.0, followed by required DSC comments including %%BoundingBox: llx lly urx ury to define the minimal rectangle enclosing all graphic marks in default user space units (typically points, where 1 point = 1/72 inch).[18] The core consists of PostScript code bracketed for safe execution via save and restore contexts, ensuring stack integrity and avoiding interference with the host document; optional elements include %%Creator:, %%Title:, and %%LanguageLevel: comments for metadata, plus device-specific previews like TIFF, PICT, or Windows Metafile for on-screen visualization without rendering the full code.[19][18] Preview formats such as EPSI use low-resolution PostScript for interchange, but processing requires a PostScript interpreter, with importing applications advised to parse comments, clip to the bounding box, and handle extensions like CMYK color support.[17]
EPS excels in scalability for vector content, delivering lossless enlargement without pixelation, and broad compatibility with design software like Adobe Illustrator and professional printers, though it lacks native transparency and demands specialized tools for editing.[16] Its proprietary yet publicly documented nature (via Adobe Technical Note #5002) has sustained adoption in print industries, but vulnerabilities to malicious PostScript code prompted restrictions, such as Microsoft disabling EPS imports in Office by 2017, and its decline stems from PDF's superior features like multi-page support and compression.[17] File extensions include .eps, .epsf, or .epsi, with magic numbers like %!PS-Adobe-3.0 for identification, and MIME type application/postscript.[17] Despite obsolescence in web contexts, EPS persists where precise, high-fidelity output is critical, such as in offset printing or vector-based archiving.[19]
Materials science
Expanded polystyrene
Expanded polystyrene (EPS) is a lightweight cellular plastic derived from polystyrene resin, consisting of approximately 98% air trapped in closed-cell polystyrene beads that are expanded and fused together.[20] It was invented in 1949 by Fritz Stastny, a chemist at BASF in Germany, who discovered that polystyrene beads impregnated with a volatile hydrocarbon could expand dramatically when heated with steam, leading to a patent for the material under the name Styropor in 1952.[21] Commercial development built on earlier work with polystyrene, first isolated in 1839 by Eduard Simon from natural resin, and advanced in the 1930s by IG Farben and Dow Chemical for solid polystyrene applications.[22] [20] The production of EPS involves three main stages: pre-expansion, maturation, and molding. Polystyrene beads, typically 0.2–0.3 mm in diameter and containing 4–7% pentane as a blowing agent, are first subjected to steam at atmospheric pressure in a pre-expander, causing the pentane to vaporize and expand the beads up to 40 times their original volume, reducing density to 15–30 kg/m³.[23] [20] The expanded beads are then allowed to mature for 4–12 hours to equalize pressure and cool, after which they are placed in a mold and steamed again at higher pressure (around 1 bar) to fuse the beads into a solid block or shape, followed by drying and cutting.[24] [25] This process yields a rigid, closed-cell foam with densities ranging from 0.90 to 1.14 pounds per cubic foot (14–18 kg/m³) for standard insulation grades, though higher densities up to 2 pcf (32 kg/m³) are possible for structural uses.[26] EPS exhibits low thermal conductivity, typically 0.032–0.040 W/(m·K) at 25°C, providing effective insulation with R-values of about 3.6–4.0 per inch of thickness, due primarily to the trapped air in its cells acting as a barrier to heat transfer.[27] [28] Its low density enables high strength-to-weight ratios, with compressive strengths of 10–60 psi depending on density, making it suitable for load-bearing applications without excessive material use.[26] The material is hydrophobic, absorbing less than 4% water by volume over long-term immersion, and offers good shock absorption from its elastic deformation under impact.[20] However, EPS is flammable unless treated with flame retardants like hexabromocyclododecane (HBCD), and it degrades under ultraviolet exposure, limiting outdoor use without coatings.[29] Primary applications of EPS include protective packaging for fragile electronics, perishables, and pharmaceuticals, where its cushioning and thermal stability minimize damage and maintain temperatures during transit.[30] [31] In construction, it serves as rigid insulation boards for walls, roofs, and foundations, accounting for roughly half of foam insulation use in residential building envelopes due to its cost-effectiveness and performance in reducing energy loss.[20] [32] Other uses encompass flotation devices like dock floats, given its density below that of water (about 16–32 kg/m³ versus 1000 kg/m³), and molded products such as helmet liners and automotive components for vibration damping.[33] [34] Environmentally, EPS contributes minimally to resource depletion as a petroleum-derived product requiring only 2% plastic resin by volume, with the rest being air, but its low bulk density complicates collection and transport for recycling.[35] It is theoretically 100% recyclable through densification into ingots for reuse in new EPS or other plastics, with end markets including construction fillers and frame moldings, though actual recycling rates remain low (under 15% globally) due to contamination and infrastructure limits.[36] [37] Mismanaged EPS waste persists in landfills and marine environments without biodegrading, fragmenting into microplastics that harm wildlife through ingestion, though its inert chemical stability prevents toxic leaching under normal conditions.[38] [39] Life-cycle assessments indicate EPS insulation reduces overall energy use and emissions in buildings by factors of 100–800 times the embedded energy of the material itself over its service life.[37]Automotive engineering
Electronic power steering
Electronic power steering (EPS), also known as electric power-assisted steering (EPAS), is a steering system that employs an electric motor to provide assistive torque to the steering mechanism, augmenting the driver's input without relying on hydraulic fluid pressure. Unlike traditional hydraulic systems, which draw continuous engine power via a belt-driven pump, EPS activates the motor only when steering assistance is required, enabling variable levels of support based on vehicle speed and steering effort—typically higher assist at low speeds for maneuverability and reduced assist at highway speeds for stability.[40][41] The primary components of an EPS system include a torque sensor mounted on the steering column to measure driver-applied force, a vehicle speed sensor for contextual input, an electronic control unit (ECU) that processes signals and computes required assist, an electric motor (often brushless DC) integrated into the steering column, rack, or pinion, and a gear reduction mechanism to amplify motor torque. Additional sensors may monitor steering angle and wheel position to enhance precision and integrate with advanced driver-assistance systems (ADAS). These elements form a closed-loop control system where real-time data ensures proportional assistance.[42][43] In operation, the torque sensor detects twisting force on the steering shaft from the driver's hands, while speed and other inputs feed into the ECU, which calculates and commands the motor to apply corrective torque via pulse-width modulation for efficient power delivery. This electromechanical assistance directly influences the rack-and-pinion or recirculating-ball gear, reducing steering effort by up to 80% under load without parasitic drag on the engine. EPS configurations vary: column-assist for lighter vehicles, rack-assist for heavier applications, and dual-pinion for high-precision needs, allowing tunable response curves for different driving conditions.[44][45] Development of EPS traces to the late 1980s, with early prototypes like a nearly production-ready system for the 1989 Pontiac Fiero, though full-scale implementation began in 1993 on the Fiat Punto, marking the first widespread production use. Subsequent adoption accelerated in the 2000s, driven by efficiency demands; by the 2010s, EPS became standard in most passenger vehicles, supplanting hydraulics in over 90% of new models globally due to regulatory fuel economy standards.[46][47][48]| Aspect | Electronic Power Steering (EPS) Advantages | Hydraulic Power Steering Disadvantages (Relative to EPS) | EPS Disadvantages |
|---|---|---|---|
| Fuel Efficiency | Eliminates constant pump drag, improving mileage by approximately 1 mpg; motor engages on-demand.[49][50] | Continuous engine-driven pump consumes power even when idle, reducing efficiency. | N/A |
| Weight and Packaging | Lighter by 10-20 kg, no fluid reservoirs or hoses; compact for better vehicle design.[51] | Heavier components and fluid lines limit space. | Complex electronics may increase initial cost. |
| Tunability and Integration | ECU allows customizable feel, speed-sensitive assist, and seamless ADAS linkage (e.g., lane-keeping).[52] | Fixed hydraulic ratios harder to adapt; no native electronic integration. | Potential for artificial "feel" lacking road feedback in some implementations.[53] |
| Maintenance | No fluid leaks or pump wear; fewer moving parts. | Prone to leaks, fluid contamination, and pump failures requiring periodic service. | Higher repair costs for electronic faults; specialized diagnostics needed.[53] |