L波段和S波段脉冲雷达的功率模块新产品

针对脉冲雷达应用,Microsemi公司PPG集团推出了系列化的L波段和S波段功率模块(PSM)。这些功率模块可输出2～3倍于当今市场上单个晶体功率管所能输出的功率,其设计采用了易于使用的"即插即用"概念,用户能够直接将其植入系统而不需进行更多的阻抗匹配设计。更高的输出功率和更高的效率,加上"即插即用"的特点能够极大地简化用户系统设计的复杂性,缩短设计周期,功放部分的尽寸缩小50%以上,并且极大地提高了用户产品的开机合格率。     

In utilizing a technetium 99m perfusion agent, are most laboratories imaging rest first and stress later, or the reverse?

We report a diagnostic sign of ulnar neuropathy. Function of the interossei is tested by asking the patient to hold a sheet of paper between the middle and ring fingers, by adducting the fingers while the examiner pulls it firmly away. The metacarpophalangeal joints will flex more on the affected side as the flexor tendons are recruited. This test can easily detect muscle weakness in the early stage of ulnar neuropathy, and is produced by a similar mechanism to that of Froment's sign.     

Cytidine deaminase from two extremophilic bacteria: cloning, expression and comparison of their structural stability

We cloned, purified and characterized two extremophilic cytidinedeaminases: CDA_Bcald and CDA_Bpsy, isolated from Bacillus caldolyticus(growth at 72°C) and Bacillus psychrophilus (growth at 10°C),respectively. We compared their thermostability also with themesophilic counterpart, CDA_Bsubt, isolated from Bacillus subtilis(growth at 37°C). The DNA fragments encoding CDA_Bcald andCDA_Bpsy were sequenced and the deduced amino acid sequencesshowed 70% identity. High sequence similarity was also foundwith the mesophilic CDA_Bsubt. Both enzymes were found to behomotetramers of approximately 58 kDa. CDA_Bcald was found tobe highly thermostable, as expected, up to 65°C, whereasCDA_Bpsy showed higher specific activity at lower temperaturesand was considerably less thermostable than CDA_Bcald. Afterpartial denaturation at 72°C for 30 min, followed by renaturationon ice, CDA_Bcald recovered 100% of its enzymatic activity, whereasCDA_Bpsy as well as CDA_Bsubt were irreversibly inactivated. Circulardichroism (CD) spectra of CDA_Bcald and CDA_Bpsy at temperaturesranging from 10 to 95°C showed a markedly different thermostabilityof their secondary structures: at 10 and 25°C the CD spectrawere indistinguishable, suggesting a similar overall structure,but as temperature increases up to 50–70°C, the -helicesof CDA_Bpsy unfolded almost completely, whereas its ß-structureand the aromatic amino acids core remained pretty stable. Nosignificant differences were seen in the secondary structuresof CDA_Bcald with increase in temperature.     

Computer‐aided simulation and testing of spatial linkages with joint mechanical errors

Tolerance allocation influences production costs in a big way. For this reason it is very important to have an accurate study about the effects of manufacturing errors on the functioning and performances of linkages. In this paper, the authors present a computer‐aided methodology based on a 3D geometrical approach using the dual‐algebra fundamentals. The purpose is to give an useful tool which can be integrated into CAD software in order to evaluate the performances of spatial mechanisms with mechanical errors. The proposed methodology has been validated by means of experimental tests on a Cardan joint mechanism with clearances, misalignments and dimensional errors. Copyright © 2005 John Wiley & Sons, Ltd.     

A sub-1-dB NF±2.3-kV ESD-protected 900-MHz CMOS LNA

A sub-1-dB noise figure HBM ESD-protected [-3 kV, 2.3 kV] low noise amplifier (LNA) has been integrated in a 0.35-μm RF CMOS process with on-chip inductors. The sensitivity of the LNA performances to the spread of parasitics associated with package and bondwire has been attenuated by using an inductive on-chip source degeneration. At 920 MHz and P_dc=8.6 mW, the LNA features: noise figure NF=1 dB, input return loss=-8.5 dB, output return loss=-27 dB, power gain G _p=13 dB, input IIP3=-1.5 dBm. At a power dissipation of 5 mW and 17.6 mW, a NF respectively equal to 1.2 dB and 0.85 dB is measured. The CMOS LNA takes 12 pins of a TQFP48 package, an area of 1.0×0.66 mm² (bondwire pads excluded) and it is the first HBM ESD-protected [-3 kV, 2.3 kV] CMOS LNA to break the 1-dB NF barrier     

Bibliometric analysis to identify an emerging research area: Public Relations Intelligence—a challenge to strengthen technological observatories in the network society

Scientometrics - Nowadays within the global economy, organizations of all kinds require strategic information to ensure that their decision making is competitive in uncertain complex environments....     

Effect of the lentil flour and hydrocolloids on baking characteristics of wholemeal durum wheat bread

In this study, the characterisation of functional bread based on wholemeal durum wheat flour enriched with lentil flour was investigated to find a good balance between the nutritional and organoleptic properties of the final product. In particular, the effect of different percentage of lentil flour (10%, 20% and 25%) and the type and amount of structuring agents (carboxymethyl cellulose, guar seed flour, pectin and tapioca starch) were studied by assessing the sensorial, textural and nutritional properties of the functional bread. Results showed that the increase in the lentil flour at 20% and 25% negatively affected the dough texture and the sensorial quality of the bread. The screening of different hydrocolloids on the bread sample enriched with 25% of legume flour highlighted that the guar seed flour at concentration of 2% allowed obtaining the best results in terms of sensory properties. The nutritional analysis of the optimised functional bread showed an increase in proteins and dietary fibre (total, soluble and insoluble), suggesting its high functional value and the possibility to propose it on a market that is constantly changing and attentive to health benefit of foods.     

The influence of lactic acid fermentation on biogenic amines and volatile compounds formation in flaxseed and the effect of flaxseed sourdough on the quality of wheat bread

The aim of the study was to investigate if differences in acidification, biogenic amines (BA) and volatile compounds (VC) occurred when Lactobacillus sakei KTU05-6, Pediococcus acidilactici KTU05-07 and Pediococcus pentosaceus KTU05-8 are used as starters in solid state fermentation of flaxseed and the impact of flaxseed sourdough on the wheat bread making process assessed.     

Antimicrobial dual-cured photopolymers of vanillin alcohol diglycidyl ether and glycerol dimethacrylate

Considering the current efforts for to develop new antimicrobial polymers from renewable resources suitable for application in environmentally friendly light-based technologies, novel dual-cured photopolymers of vanillin alcohol diglycidyl ether and glycerol dimethacrylate are developed. The kinetics of the sequential and simultaneous dual-curing processes, combining free radical and cationic photopolymerizations, is investigated by real-time photorheometry. Comparison of dual-curing systems with different ratios of biobased epoxy and acrylate monomers revealed that the increase in the acrylate content increases the photocuring rate and improves the mechanical performance (Young's modulus increases from 76.64 to 190.71 MPa) and thermal stability (the 10% weight loss increases from 227 to 274°C) of the polymers, while the increase in the vanillin epoxy content results in better antimicrobial activity. Developed photopolymers create unfavorable conditions for the growth of microorganisms and reduce their population by up to 0% in 24 h. The excellent antibacterial and antifungal activity of new photopolymers allows them to be considered as biobased alternatives to petroleum-based antimicrobial coatings, films, or optical 3D printed objects.