TV-SAT, CCTV, WLAN Dipol Weekly Review

New polymer protects against corrosion.

Scientists at MIT have developed an ultrathin polymer coating that proves to be almost completely impermeable to gas molecules. The discovery paves the way for the creation of extremely effective barriers to protect electronic devices from corrosion, extend the shelf life of food and medicines, and protect buildings, vehicles or ships from the effects of weather conditions.
The material can be applied as a film only a few nanometres thick. Tests have shown that, in practice, it completely repels nitrogen and other gas molecules - up to the limits of modern measuring equipment. Such low permeability has not yet been observed in any polymer and rivals crystalline materials such as graphene. Significantly, although the material is formed by polymerisation in solution, it behaves like graphene, which is impermeable to gases thanks to its perfectly ordered structure. However, the polymer itself does not resemble a crystal at all - yet it exhibits similar barrier properties. Unlike graphene, the new film can be produced on a large scale and can be easily applied to a variety of surfaces, making it a much more practical material for protective applications.

The new material is a so-called 2D polyarimide (2DPA-1), a two-dimensional polymer that self-assembles into ordered sheets through hydrogen bonds. It is formed from melamine, a compound containing a ring of carbon and nitrogen atoms. Under the right conditions, the monomers grow in two dimensions to form nanometre-sized disks, which then form tightly into stable layers.
The material is stronger than steel, yet has a much lower density. Even in early tests, it was noted that it was distinguished not only by its strength, but also by its remarkable gas tightness. To confirm this, researchers created microscopic bubbles from the polymer and filled them with gas. In typical polymers, such as plastics, the gas penetrates the material over time, leading to the bubble collapsing. Meanwhile, the 2DPA-1 vesicles created in 2021 remain intact to this day.
Typical polymers resemble tangled fibres, between which microscopic spaces remain to allow gases to move freely. In the case of 2DPA-1, the situation is different: the polymer forms flat, tightly adherent disks. The lack of free spaces between them makes the material virtually impervious to gases.

The discovery of this polymer could prove to be a breakthrough in materials engineering - it combines lightness, strength and near-absolute gas permeability in a single material that can be easily and economically produced on a large scale. Tests conducted with a variety of gases, such as helium, argon, oxygen or methane, showed permeability at least 10,000 times lower than that of the best available polymers. This opens up a wide range of application perspectives for the material.
In the energy sector, it can serve as a coating to protect perovskites - modern, lightweight and low-cost materials for solar panels, but which are prone to rapid decomposition. A 2DPA-1 layer of just 60 nanometres extended their life by several weeks, and thicker coatings could provide even longer protection. In the infrastructure sector, the material could protect bridges, buildings, as well as vehicle and ship components, wherever weathering and corrosion resistance is crucial. In the food and pharmaceutical industry, meanwhile, it could significantly extend the freshness and shelf life of oxidation-sensitive products.

Mounting SIGNAL PRO multiswitches in a telecommunication cabinet.

Multiswitches of the SIGNAL PRO series are devices designed for distribution of satellite and terrestrial signals in SMATV systems. They are properly installed using specially designed brackets, and one of them is UCH PRO 1 R69985. This bracket enables quick, stable and orderly mounting of two multiswitches in telecommunication cabinets, as well as on flat surfaces in dual-layer system. Thanks to its design, it provides adequate distance between the device and the substrate, improves air circulation and facilitates the routing of coaxial cables. Its rigid construction guarantees stability even with a large number of cables fed into the multiswitches, reducing the risk of stress on the connectors.

Advantages of mounting multiswitches SIGNAL PRO on a bracket:

Use of relay outputs in the Hikvision DS-KH6320-WTE1 IP video door entry monitor.

When installing a video door entry system, there is sometimes a need to install additional signalling to inform the user that someone has pressed the call button at the door station. Examples include installing the system in a noisy production hall, being used by a hearing impaired person or wanting to install a signalling system outside the house, so that when you are in the garden you realise someone has arrived.

The DS-KH6320-WTE1 video door entry monitor has two built-in relays that can be activated when it starts ringing when a call button is pressed. These relays can operate in monostable (1-180 s) or bistable mode. The operating time and mode of each relay can be configured individually. For example, one relay can be connected to an acoustic signal with an operating time of 5 s and another to an optical signal with an operating time of 60 s. Associating the relays with the call button can be done using the iVMS-4200 application, after entering the remote settings of the monitor in the tab: Domophone -> Link association. There, select the /// option and select the relay output to be activated when the call is made. Configuration of the relay mode and operating time, is possible directly from the monitor.

What kind of knife for mechanical splices?

Mechanical splices for connecting optical fibers are still a popular solution used by installers who occasionally perform installations based on fiber optic cabling. A common question that arises when first shopping for mechanical splicing accessories is that of choosing a fiber cutter.

The fibre cutter regardless of the version is the most expensive part of the kit, so it is worth paying a little more attention to it. There are 2 types of knives to choose from:

The L5882 cutter is used when splicing fibers with a fiber optic splicer. It guarantees very good quality and repeatability of cutting. Despite this, the use of this type of knife for mechanical splicing does not seem to be a good idea. In a situation where the guillotine is used with a welding machine, the installer gets feedback that the knife is cutting badly as a result of the blade becoming unsettled or blunted. It is also possible that the blade does not cut at all. It is then necessary to properly adjust the blade. However, this is not possible without having a splicer and verifying the effects of adjusting the setting on the splicer's screen. Therefore, using the L5882 knife for mechanical welding runs the risk of unknowingly making poor cuts that can have a real impact on the quality of the splice.

In contrast, the L5801 knife does not require any adjustment. Its initial cut quality is inferior to that of the L5882, but acceptable when performing mechanical splicing. The cuts are not so repeatable, some of them could be rejected by a thermal splicer, but in the vast majority of cases the quality of the cut is quite sufficient to perform a mechanical splice.

Buffer power supply for mobile systems. Vehicles sometimes have additional systems installed, such as a mobile DVR, network devices, LTE routers, communication modules or other systems that require a constant power supply. To ensure their continuous operation irrespective of the ignition status, ATTE has developed the LVUPS-140-UN1-OF M18725 universal buffer module for use with 12 V or 24 V vehicle installations. Its main task is to ensure continuity of power supply to network devices - both while driving and when the vehicle is stationary. This ensures that the monitoring system remains active even when the engine is switched off, without the risk of discharging the main car battery...>>>more