Test Detects COVID-19 in 30 Seconds
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This antibacterial coating for the titanium screw that attaches the new implant to the bone of the jaw reduces the progression of peri-implant disease, which can lead to bone loss and eventual loss of the implant. Implants are a more common replacement for missing teeth than traditional fixed or removable dental prostheses. Approximately five percent of all dental implants anchored through osseointegration, or the attachment of human bone cells to a metal surface, will fail within ten years. Peri-implantitis, a degenerative, site-specific bacterial infection with no treatment options, causes inflammation of soft-tissue around the implant and bone loss following installation, making it the main cause of failed implants. Available implants traditionally use screws with a coating of titanium-nitride, which reduces corrosion and has good biocompatibility to help osseointegration. However, in those cases where peri-implantitis develops it can lead to loss of bone as well as failure of the implant. Attempts to coat the screw with charged metallic particles with antibacterial properties, such as copper, silver or magnesium, resulted in unfavorable interactions with surrounding tissue.
Researchers at the University of Florida have developed a titanium-nitride coating incorporating an antibacterial layer of quaternary nitrogen that has improved antiseptic properties without using charged metallic ions. Preliminary data indicates that the positively charged quaternized TiN outperforms traditional TiN coatings with a 40-50 percent reduction in bacteria.
Antibacterial dental implant coating that will reduce peri-implant disease and increase implant lifetime
The formation of the antimicrobial layer relies on producing a charged titanium-nitride (TiN) surface through a Menschutkin reaction, which is commonly used to synthesize quaternary ammonium salts. Creation of a charged TiN surface requires three steps. First, a titanium vapor solidifies, forming the titanium layer. Next, a titanium-nitride (TiN) layer forms through evaporation, chemical vapor deposition, plasma spray or sputtering, which coats the titanium layer. Finally, the titanium-nitride (TiN) quarternizes through a reaction of the titanium-nitride layer with an alkyl halide.
This gas sensor detects ammonia gas by utilizing a highly electron mobility transistor (HEMT), a device used to amplify or switch electronic signals and electrical power. Ammonia gas is used to reduce nitrogen oxides (NOx) through selective catalytic reduction (SCR) to prevent acid rain and smog formation. Various industries currently use ammonia gas to reduce emissions from boiler flue gases, refinery off-gas combustion, gas and diesel engines, gas turbines in the power industry and chemical process gas streams and more. However, monitoring and detecting ammonia gas is a required step in the process because high concentrations of ammonia in the environment can cause pollution and be toxic to terrestrial and aquatic organisms. Additionally, ammonia is flammable and can cause respiratory issues. In 2013, an ammonia fertilizer company exploded in Texas, killing 15 people and injuring more than 260 people.
Researchers at the University of Florida have developed a gas sensor that contains a highly sensitive and thermally stable GaN based HEMT with ZnO nanorods on the gate region of the sensor. This invention detects ammonia gas and other nitrogen compounds at low concentrations, preventing uncontrolled levels from harming the environment. Detection of ammonia at low concentrations is necessary for the refrigeration, agricultural, automotive, and chemical industries.
Gas sensor utilizes ZnO functionalized HEMT to increase detection sensitivity of ammonia gas
These gas sensors use GaN based HEMTs for low concentration ammonia detection. A layer of ZnO nanorods are used as functionalized gates to sense and measure ammonia concentrations. When exposed to ammonia, the conductivity of ZnO changes, causing the voltage readings from the sensor to change. The sensor works quickly and alerts its users when low levels of gas are present. The device can operate in harsh environments with high temperatures and receive no interference from other gases. This invention works both smoothly and efficiently, enabling its use in a variety of applications that require ammonia detection.
This coating for medical implants minimizes surface corrosion and inhibits the formation of bacterial biofilm while maintaining biocompatibility. The global medical device coatings market is expected to reach $17.4 billion in value by 2023 . The largest segment of this market is anti-microbial coatings, which dental or orthopedic implants employ to reduce the risk of infection and need for premature replacement. Implant coatings must inhibit bacterial growth but not impair survival and growth of cells in the recipient tissues. Many available coatings that afford strong antibacterial properties release ions that are toxic to mammalian cells. For dental and orthopedic implants, coatings that have good antibacterial activity, but are also biocompatible as well as providing corrosion-resistance are hard to find.
Researchers at the University of Florida have discovered that a very thin coating of silicon carbide (SiC) prevents the formation of bacterial biofilm without disrupting healthy mammalian cell adhesion or proliferation. The SiC coating has additional corrosion and abrasion resistant properties that increase durability of an implant.
Biocompatible implant coating to protect against bacterial infection and corrosion
The silicon carbide coating applies to an implant surface by plasma-enhanced chemical vapor deposition (PECVD). Quaternizing the SiC coating by adding nitrogen atoms to the SiC surface coatings during PECVD further increases the coating’s antimicrobial properties. The SiC surfaces are corrosion and wear-resistant and exhibit greater hydrophobicity than non-coated surfaces, minimizing the formation of biofilm. In one study, SiC coated materials exhibited a biofilm coverage of 16.9 percent whereas uncoated samples displayed coverage of 91.8 percent after 24 hours.
This poly(methyl methacrylate) (PMMA)-encapsulated Schottky diode protects hydrogen sensors from humidity without affecting their ability to detect hydrogen. Hydrogen is a source of energy that powers different forms of transportation, buildings and industrial processes making it a valuable resource. However, hydrogen can become problematic because it is highly reactive, flammable, has low ignition energy, and has a high tendency to leak. Hence, it is crucial that efficient detection technologies are available to ensure the safe use of hydrogen. One of the biggest issues with GaN-based hydrogen sensors is their sensitivity to humidity. Exposure to ambient humidity significantly decreases the sensitivity because water molecules block the active sites of the sensor. Researchers at the University of Florida have enclosed hydrogen sensing diodes with PMMA to effectively mitigate the effects of water. This enables the sensors to work in a variety of humid environments and allows them to be modified to detect other gases.
Encapsulation of Pt-AlGaN/GaN Schottky diodes with water-blocking polymer layer provide a moisture barrier for gas sensors
This Schottky diode is completely enclosed in PMMA, which creates a barrier between the sensor and any source of water or moisture, preventing excess background noise and corrosion. The PMMA coating allows hydrogen molecules to diffuse through and reach the sensor while preventing water molecules from reaching the diode. By eliminating this problem, the hydrogen sensor has an increased range of environments in which it can be used and provides more precise measurement.
Devices fabricated that use this backside source field plate method operate at higher voltages and with better reliability due to the lower peak electric field and junction temperature. Field-effect transistors such as AlGaN/GaN high electron mobility transistors (HEMTs) have received increasing attention for high power and high frequency applications (i.e. military radar or satellite-based communications systems) due to their superior mobility and larger energy band gap as compared to Si-based power transistors. GaN epi-layers are usually grown on sapphire, silicon (Si), or silicon carbide (SiC) substrates. Of the three, silicon substrates are the most promising as a prime candidate for mass production of GaN, but the nucleation interfacial layer between GaN and Si causes inefficient heat dissipation. University of Florida researchers have overcome this deficiency by adding a Si-substrate via hole under the active area of the HEMT to decrease the junction temperature and dissipate the heat directly through the device’s active area. The modification reshapes the electric field in the channel, reduces the peak value on the drain side of the gate edge, and reduces the gate to drain capacitance. Depending on the requirement for specific applications, the backside field plate technique is applicable to forming gate or drain field plates as well with simple modifications.
Backside via hole technique for field effect transistors with improved heat dissipation and reliability
This semiconductor device and technique for a HEMT with improved heat dissipation includes a number of fabricated layers – the nucleation layer, the transition layer, a buffer, and a barrier -- built upon a substrate. Researchers etch the back side of the substrate to form a via hole through the substrate under the gate or active region of the HEMT through the layers and then fill the hole with metal. The metal-filled via hole decreases the junction temperature and dissipates the heat directly through the device’s active area.
This prebiotic agent can prevent and treat oral diseases by eliminating disease-causing bacteria, while simultaneously promoting the growth of healthy bacteria. An estimated 3.9 billion people worldwide suffer from oral diseases such as cavities, oral thrush, peri-mucositis and peri-implantitis. These diseases result from an imbalance in the bacterial communities living on the teeth characterized by overabundance of acid-producing, cavity-causing (cariogenic) bacteria at the expense of the bacteria that dislike acidic environments and produce bases. Conventional treatment of oral diseases proceeds by brute force removal of the entire bacterial community, but unfortunately this removes the healthy base-producing bacteria as well as the cavity-causing species they counter. Selectively removing disease-causing bacteria would be a better route to easing the burden of oral diseases.
Researchers at the University of Florida have developed N-Acetyl-Glucosamine (GlcNAc) as an easy-to-use prebiotic remedy for the treatment and prevention of diseases caused by oral bacteria. This treatment selectively targets cavity-causing bacteria by hindering their metabolism, while at the same time acting as a nutrient source for healthy base-producing bacteria. This restores the natural balance of the bacterial community without destroying it, yielding better oral health.
Treatment and prevention of cavities and other oral diseases stemming from imbalanced oral bacteria communities
Common preventable diseases such as cavities and oral thrush stem from an imbalance in the microbes living on the teeth and other oral surfaces in a community known as a biofilm or plaque. This microbiome balances its pH by countering acid-producing bacteria, also called cariogenic bacteria, with base-producing bacteria, also called commensals. However, excessive proliferation of cariogenic bacteria shifts the composition and sugar metabolism of the biofilm, forming an acidic plaque, which eventually causes cavities. Similarly, loss of microbial balance is also the underlying cause of periodontitis and several other oral diseases that are of global public health importance.
Bacteria readily metabolize the prebiotic carbohydrate N-Acetyl-Glucosamine (GlcNAc). During metabolism, GlcNAc induces physiological reprogramming in plaque-producing bacteria that slows acid production, but stimulates commensal bacteria to produce antimicrobial and alkalizing compounds such as hydrogen peroxide H2O2 and ammonia NH3, respectively. These compounds act against the proliferation of cariogenic bacteria and other potential pathogens, providing an additional push toward rebalancing the biofilm.
GlcNAc delivery is versatile enough for both professional and at-home use. For example, administration of GlcNAc in the form of mouthwash or toothpaste can be carried out at home by the patient. Alternatively, a hydrogel formulation can be used less frequently and would be appropriate for patients who are unable to care for themselves.
These self-repairing semiconductor designs can be integrated into computer processors for radio communication in high temperature or high radiation environments. Worldwide sales of semiconductors in 2014 reached $335.8 billion, up 9.9 percent from 2013. Low-power satellites in outer space, cell phones and towers, or rugged military laptops use the toughest semiconductors available. They relay important information, such as GPS coordinates or digital messages. Because of hostile environmental conditions, quick temperature changes, and normal wear and tear, this expensive equipment needs regular replacement. Semiconductor manufacturers often use Gallium Nitride-based HEMT (High-electron-mobility transistor) semiconductors for radio frequency communications and direct current power. HEMTs are fast and resistant to noise, but HEMTs are not immune to all threats. Stresses such as moisture, localized heat, and voltage spikes might decrease processor performance, increase power consumption, and eventually lead to circuit failure. Thermal annealing -- applying a uniform heat source -- can undo some of that damage, but available methods are not feasible. Researchers at the University of Florida have developed an on-chip heater with a preset drain or gate current level. Now, whenever semiconductor chips conditions reach that preset level, an internal heater could turn on automatically and begin annealing the chips. After annealing, these chips could return to near-original electrical operating condition. No outside maintenance by the device owner would be needed.
High-performance, longer-lasting, self-repairing semiconductors for RF communication, AC to DC power conversion, and DC power amplification
The patent-pending semiconductor designs include an on-chip or on-substrate heater with a preset drain or gate current level. When the semiconductor conditions reach the preset level, the heater will automatically turn on and thermally anneal the chips. Research shows annealing will reverse or partially reverse effects such as forward and reverse bias current increase, the appearance of traps, sub-threshold swing increase, sub-threshold leakage increase, reverse bias gate leakage current increase, saturation drain current reduction, drain current on-off ratio reduction, gate current reduction, lower electromagnetic Schottky barriers, higher diode ideality factors, weaker small signal RF, and degradation at a metal-Aluminum Gallium Nitride interface. Overall, since a chip can regain lost performance even after multiple heat treatments, its life expectancy will increase.
