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This article discusses the discovery of phosphorescent lithopone on watercolor drawings by American artist John La Farge dated between 1890 and 1905 and the history of lithopone in the pigment industry in the late 19th and early 20th centuries. Despite having many desirable qualities for use in white watercolor or oil paints, the development of lithopone as an artists’ pigment was hampered by its tendency to darken in sunlight. Its availability to, and adoption by, artists remain unclear, as colormen's trade catalogs were generally not explicit in describing white pigments as containing lithopone. Further, lithopone may be mistaken for lead white during visual examination and its short-lived phosphorescence can be easily missed by the uninformed observer. Phosphorescent lithopone has been documented on only one other work-to-date: a watercolor by Van Gogh. In addition to the history of lithopone's manufacture, the article details the mechanism for its phosphorescence and its identification aided by Raman spectroscopy and spectrofluorimetry.

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  • Additionally, urban areas are increasingly facing challenges related to stormwater management due to impervious surfaces like asphalt and concrete. Storm drain covers that incorporate sustainable design features, such as permeable materials, can help mitigate these challenges. Permeable covers allow water to seep through into the ground, reducing runoff and recharging groundwater supplies.


  • In summary, drain cover hooks are vital components of urban infrastructure that significantly enhance safety, accessibility, and environmental stewardship. While they may often go unnoticed, their presence and functionality are essential in preventing accidents, facilitating efficient maintenance, and protecting our natural resources. As cities continue to grow and evolve, it is imperative that we recognize the multifaceted roles of such seemingly mundane components and advocate for their consistent use in public spaces. By doing so, we contribute not just to safer cities but to a more sustainable urban future.


  • Another significant aspect of gate valves in firefighting systems is their durability and ability to operate under extreme conditions. Firefighting environments can be hazardous, with high heat and pressure. Gate valves are constructed from robust materials, making them resistant to heat and corrosion. This robustness ensures that they will function correctly when needed most, providing peace of mind to firefighters and those they protect.


  • The location of a sewer manhole must be carefully considered to ensure that the drainage system is effective and easy to maintain.[14][15] According to design standards, the distance between two manholes is typically between 7 and 20 meters, depending on the specific characteristics of the project.[16][17] In cities, the distance is 20 meters per manhole,[18] while in industrial or commercial settings it is 10-15 meters per manhole.[19][20] The distance between manholes in homes or restaurants is typically 7-10 meters.

  • Telescopic security posts, often made from durable materials such as stainless steel or heavy-duty plastic, are retractable barriers that can be raised or lowered as needed. They are commonly used to control vehicle access in high-security areas, such as airports, government buildings, and corporate headquarters. When deployed, these posts serve as a physical barrier to prevent unauthorized vehicle entry. When retracted, they allow for unobstructed access, demonstrating their versatility.


  • Bollards can be categorized into different types based on their intended use and construction. Fixed bollards are permanent installations, designed to withstand significant force from vehicles while maintaining their position. They are typically constructed from durable materials such as steel or concrete, ensuring long-lasting protection.


  • Removable bollards are posts designed to control or restrict vehicle access to certain areas while allowing for pedestrian movement. They can be manually removed and reinstalled, making them a flexible option for spaces that require variable access control. Unlike fixed bollards, removable versions offer greater versatility, making them ideal for situations where temporary vehicle access is necessary, like during public events or for service vehicles in private lots.


  • 1. Assess Your Needs Before purchasing a second-hand bike rack, consider how you plan to use it. Do you need to carry one bike or multiple? Will you use it for cycling trips, commuting, or both? Understanding your requirements will help you choose the right rack type—be it a roof-mounted, hitch-mounted, or trunk-mounted rack.


  • Choosing the right trunk bike carrier depends on several factors, including the number of bikes being transported, the type of bicycles (e.g., mountain bikes, road bikes), and personal preferences regarding features. It's essential to research and compare different models, taking into account factors such as weight capacity, ease of use, and customer reviews. Many manufacturers offer a range of products catering to different needs, so prospective buyers can find a model that perfectly suits their requirements.