Peroxynitrite mediates programmed cell death both in papillar cells and in self-incompatible pollen in the olive (Olea europaea L.)

Programmed cell death (PCD) has been found to be induced after pollination both in papillar cells and in self-incompatible pollen in the olive (Olea europaea L.). Reactive oxygen species (ROS) and nitric oxide (NO) are known to be produced in the pistil and pollen during pollination but their contribution to PCD has so far remained elusive. The possible role of ROS and NO was investigated in olive pollen–pistil interaction during free and controlled pollination and it was found that bidirectional interaction appears to exist between the pollen and the stigma, which seems to regulate ROS and NO production. Biochemical evidence strongly suggesting that both O2˙− and NO are essential for triggering PCD in self-incompatibility processes was also obtained. It was observed for the first time that peroxynitrite, a powerful oxidizing and nitrating agent generated during a rapid reaction between O2˙− and NO, is produced during pollination and that this is related to an increase in protein nitration which, in turn, is strongly associated with PCD. It may be concluded that peroxynitrite mediates PCD during pollen–pistil interaction in Olea europaea L. both in self-incompatible pollen and papillar cells

Suicide risk and prevention during the COVID-19 pandemic

No abstract available

An SiGe/Si Heterojunction Phototransistor for Opto-Microwave Applications:Modeling and first Experimental Results

A first SiGe bipolar heterojunction phototransistor developed in a commercial available SiGe/Si technology is presented.Emphasis on the development of a complete numerical model for the simulation of strained- SiGe based devices is given.The SiGe HPT exhibits a dc opto-microwave power gain of 3.46dB,i.e.a responsivity with 50Ohms loads of 1.49A/W,and a –3dB bandwidth of 0.4GHz at 940nm.Power budgets are drawn with the use of the opto-microwave power gain ’s monogram chart

Polymerization reactor: The influence of \u201cgel effect\u201d in batch and continuous solution polymerization of methyl methacrylate

This article describes the influence of gel effect in the free radical polymerization of methyl methacrylate. A mathematical model has been developed which tries to predict the performance of batch and continuous polymerization reactors under dynamic and steady-state conditions. The influence of diffusion phenomena on the process kinetics (gel effect) is very important. The autoacceleration in the polymerization rate of the batch reactor and the mulitple steady state for the continuous stirred tank reactor (CSTR) are connected with the attainment of critical conditions in the system. Such a model is useful for the design of the reactor and the choice of the control system

Polymerization reactor: The influence of "gel effect" in batch and continuous solution polymerization of methyl methacrylate

This article describes the influence of gel effect in the free radical polymerization of methyl methacrylate. A mathematical model has been developed which tries to predict the performance of batch and continuous polymerization reactors under dynamic and steady-state conditions. The influence of diffusion phenomena on the process kinetics (gel effect) is very important. The autoacceleration in the polymerization rate of the batch reactor and the multiple steady state for the continuous stirred tank reactor (CSTR) are connected with the attainment of critical conditions in the system. Such a model is useful for the design of the reactor and the choice of the control system

Frequency response enhancement of a single strained layer SiGe phototransistor basedon physical simulations

An original approach based on a physical model is used to evaluate opto-microwave performances of avertically illuminated single strained layer SiGe HPT. Analysis of optomicrowave performance is presented at 940nm. The contribution of each regionon the dynamic performances is studied. Frequency response enhancement is shown for base optical detection first and also by wavelength analysis while maintaining whole component detection. Increases up to a 9. 8 factor for the transition optical frequency (fTopt)in phototransistor mode are presented, reaching respectively 19.7 GHz and 15.3 GHz