Biosensors meet people's requirements. At present, quite a few biosensors have been used in environmental monitoring. In water monitoring and operation control of sewage treatment plants, biochemical oxygen demand is also one of the most commonly used and important indicators.
In recent years, the problem of environmental pollution has become increasingly serious, and serious environmental pollution has also caused a great impact on people's lives. Many diseases are caused by environmental factors. The monitoring of environmental pollution cannot be ignored. Now biosensors meet people's requirements, and a considerable number of biosensors have been used in environmental monitoring.
â‘´Water environment monitoring
Biochemical Oxygen Demand (BOD) is a widely used comprehensive indicator to characterize the degree of organic pollution. In water body monitoring and operation control of sewage treatment plants, biochemical oxygen demand is also one of the most commonly used and important indicators. The routine BOD measurement requires a 5d incubation period, and the operation is complicated, the repeatability is poor, time-consuming and laborious, and the interference is large, which is not suitable for on-site monitoring. SiyaWakin et al. Used a Trichosporoncutaneum and Bacilluslicheniformis to make a microbial BOD sensor. The BOD biosensor can accurately measure the concentration of glucose and glutamic acid at the same time. The measurement range is 0.5-40mg / L, and the sensitivity is 5.84nA / mgL. The biosensor has good stability. In 58 experiments, the standard deviation is only 0.0362. The required reaction time is 5-lOmin.
NO3 ion is one of the main water pollutants. If added to food, it is extremely harmful to human health. Zatsll et al. Proposed an integrated enzyme function field effect tube device to detect NO; ion method. The detection limit of the device for NO and ions is 7x10 minus 5 mol, the response time is less than 50s, and the system operation time is about 85s. In addition, there are reports that Han et al. Fixed Pseudomonas on the ion-grabbing electrode , Real-time monitoring of trichloroethylene in industrial wastewater, the detection range is 0.1 to 4mg / L, and the detection time is within 10min.
⑵Atmospheric environment monitoring
Sulfur dioxide (S02) is the main cause of acid rain and acid mist formation, and the traditional detection method is very complicated. Martyr et al. Fixed subcellular lipids (liver microsomes containing sulfite oxidase) on cellulose acetate membrane, and made an amperometric biosensor with oxygen electrode to detect the acid rain and acid mist sample solution formed by S02. lOmin can get stable test results.
NOx is not only one of the causes of acid rain and acid mist, but also the culprit of photochemical smog. Charles et al. Used a microbial sensor composed of a porous permeable membrane, immobilized nitrifying bacteria and an oxygen electrode to determine the content of nitrite in the sample, thereby inferring the concentration of NO = in the air. The detection limit is 0.01xl0 min 6th power mo1 / L.
What is a wireless AC controller? What does it do?
Wireless AC controller is a kind of network device, such as the AC100/150 of Fengrunda, which can be used to centrally control and manage wireless aps. It is the core of a wireless network and is responsible for managing all wireless aps in the wireless network. AP management includes: delivering configuration, modifying related configuration parameters, RF intelligent management, and access security control.
Why use a wireless controller, and what exactly does it do?
In fact, the role of the wireless controller is to play a gateway function between the WLAN and the Internet (on the router), and the data from different access points are aggregated and accessed to the Internet. The role of an access point (AP) is to complete wireless access, and it can control user access through network flags.
The role of wireless controllers
1, Flexible networking mode and excellent scalability
The AP does not need to be directly connected to the AC, so that the AP can be deployed in any place that needs to be covered through the network, such as you deploy an AP in each employee's home, and then connect to the wireless controller inside the enterprise through the VPN, you can expand the wireless network of the enterprise to the family of each enterprise member.
2, intelligent RF management functions, automatic deployment and fault recovery
Through the dedicated RF management module, we can initially estimate the AP deployment according to the user's architectural design drawing, and can calculate the average bandwidth of the wireless terminal, the coverage between AP and AP in the actual debugging process.
3. Centralized network management
All the configuration of the wireless network can be completed by configuring the wireless controller. For example, enable, manage, and maintain all AP devices and mobile terminals, including all functions such as radio wave spectrum, wireless security, access authentication, mobile roaming, and access users.
4, powerful roaming function support
The wireless controller uses AP as the boundary combined with fast RF management system, which greatly reduces the connection time between wireless client and AP, and thus realizes the function of fast roaming.
5. Load balancing
AP and wireless controller systems can distribute wireless users or terminals to nearby aps within the coverage area of an AP, ensuring the number of each wireless terminal or the sum of AP bandwidth transmission or the upper limit of each wireless terminal bandwidth.
6, wireless terminal positioning, rapid fault location and intrusion detection
Wireless controllers can track and locate the location of wireless terminals, such as wirelessly connected computers, PDAs and Wi-Fi mobile phones.
7, powerful access and security policy control
At present, the wireless system supports authentication of 802.1, WEB authentication, MAC, SSID, VPN, etc., and supports various encryption modes such as WEP, WPA, WPA-PSK, WPA2, etc., and all configurations can be configured globally through the wireless controller.
8, Qos support
AP and wireless switching systems can limit the maximum bandwidth of a user's wireless connection within each user's privileges. For different IP services, the system can also define different QoS queues through the wireless switch module. For example, for wireless voice applications, SIP and RTP protocols can be set in the high queue, while common applications such as http and ftp can be set in the low queue.
The wireless controller AC is more advanced than the AP, plays the role of manager in the wireless network, and the wireless controller AC also acts as a client to complete a series of functions in the wired network (such as authentication, authentication, etc.). However, wireless controller AC is not a WLAN device specified in the 802.11 protocol family, but as a supplement to the protocol in specific applications, and its price far exceeds that of ordinary access point (AP) devices.
In small-scale wireless networks that use only a few aps, it is not economical to use expensive wireless controller AC equipment. However, if the number of wireless aps is large, more than 20 can be used AC controller.
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