High process gain opto-electronic matched filters for communications applications

This paper is concerned with the application of opto-electronic signal processing to a certain class of interference-resistant communications techniques. The processing techniques are applicable to spread spectrum digital transmissions which are processed by a matched filter at the receiver. The analysis of optical delay line matched filters of the diffraction type is discussed. The analysis considers the basic ultrasonic light modulator, that is, the modulation of a light source by a sonic wave. The sonic wave may represent a received spread spectrum signal or received noise or a combination of both. Two ultrasonic modulators in cascade perform the desired correlation or matched filter function. The analysis considers the effects of intermodulation of signal and noise and also the effects of the beamspreading and attenuation of the sonic signal in the delay lines. Finally, the design of a matched filter having 40 dB process gain is presented together with an estimate of its communications performance.Notation angular frequency of light source - wavelength of light source - t time - velocity of sonic wave - s ₁(t)+ ₁ phase of signal input to first delay line - n(t) phase of noise input to first delay line - s ₂(t)+ ₂ phase of signal input to second delay line - ₁, ₂, _n angular frequencies of the carriers ofs ₁(t),s ₂(t) andn(t) respectively - ₁, ₂, _n wavelength, in quartz, corresponding to ₁, ₂ and _n respectively - ₁, ₂, _n maximum change in refractive index due to signals corresponding tos ₁(t),s ₂(t) andn(t), respectively - J _r(X) Bessel function of first kind, orderr and argumentX - L width of sonic beam in direction of incident light - SNR signal-to-noise ratio - IM intermodulation - IMN intermodulation noise - M process gain factor - f _c,_c frequency and wavelength of sonic carrier - 2f _d bandwidth of sonic signal - m f _d/f_c - Kbps kilo-bits-per-second - Mbps mega-bits-per-second - Kpps kilo-pulses-per-second The studies reported in this paper were performed under contract AF30 (602)-4268, Optical Signal Processing, under the direction of Mr R. R. Menard of Rome Air Development Center, Rome, New York, USA.Presented at AGARD (NATO) Avionics Panels, XVIIth Technical Symposium, Tonsberg, Norway, 1969.     

A study of some parameters relevant to the response of harwell PMMA dosimeters to gamma and electron irradiation

The effects on the radiation response of Harwell polymethylmethacrylate (PMMA) dosimeters of dose-rate, radiation type, temperature during irradiation and post-irradiation storage, and post-irradiation stability, are of importance to the operators of commercial irradiation facilities.

This paper describes recent studies of the effects of some of these parameters on the radiation response of Harwell Red 4034, Amber 3042, and Gammachrome YR Perspex dosimeters, and provides data on batch to batch variation and shelf-life.     

Regioselective synthesis of N-substituted-4-substituted isothiazolidine-1,1-dioxides

A novel and efficient synthesis of a range of racemic and enantioenriched N-substituted-4-substituted isothiazolidine-1,1-dioxides from epoxides and sulfonamides is described. The critical choice of the activating group for the cyclization event is discussed. The application of this methodology to the synthesis of N-substituted-4,5-disubstituted derivatives is also described.     

Analysis of 8-aminonaphthalene-1,3,6-trisulfonic acid labelled N-glycans by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

Fluorophore-assisted carbohydrate electrophoresis (FACE) is a fast and efficient analytical method which is now widely used in glycobiology for the separation and quantification of free or glycoprotein-released oligosaccharides. However, since identification by FACE of N-glycan structures is only based on their electrophoretic mobility after labelling with 8-aminonaphthalene-1,3, 6-trisulfonic acid (ANTS), co-migration of derived glycans on gel could occur which may result in erroneous structural assignments. As a consequence, a protocol was developed for the fast and efficient matrix-assisted laser desorption/ionisation time-of-flight (MALDI-TOF) mass spectrometric analysis of ANTS-labelled N-glycans. N-Glycans were isolated from plant and mammalian glycoproteins, reductively aminated with the charged fluorophore 8-aminonaphthalene-1, 3, 6-trisulfonic acid (ANTS) and separated using high resolution polyacrylamide gel electrophoresis. The ANTS-labelled glycans were eluted from FACE gel slices and then analysed by MALDI-TOF mass spectrometry in negative ion mode. Using 3-aminoquinoline containing 2.5 mM citrate NH(4)(+) as matrix, neutral N-linked N-glycans, as well as labelled sialylated oligosaccharides, were found to be easily detected in the 2-10 picomole range giving rise to ?M - H(-) ions.     

The tin-collection scheme for the determination of platinum-group metals, gold and silver

A comprehensive analytical scheme is presented for the determination of the six platinum-group metals, gold and silver. It is the result of the integration of separate procedures that have been described previously, in part, over the course of several years. The analytical scheme has been thoroughly tested in umpire and standards work on a wide variety of materials and, as a consequence, is of increasing interest to many laboratories. The precious metals are collected in molten tin when the sample is fused at 1200-1250 degrees with a flux containing stannic oxide, sodium carbonate, silica, borax and flour. The resultant tin alloy is dissolved and the precious metals are isolated by ion-exchange, solvent extraction and/or distillation procedures. With the exception of the usual facilities required in the fusion step of fire assaying, standard equipment can be used in the wet-chemical operations for the isolation and determination of the individual precious metals.     

CTAB反相微乳液中水辛烷分子的自扩散研究

利用电导测量确定了CTAB/正丁醇/正辛烷/水四组分体系的相态,在反相微乳液区有明显的渗滤现象,通过脉冲梯度场核磁共振方法研究了反相微乳液中水和辛烷分子的自扩散行为,采用双指数拟合得出辛烷的自扩散系数。对于体系中出现的渗滤现象以及水和辛烷分子自扩散系数反常的原因,从分子水平上进行了解释。水和自扩散系数(2～7×10^-10m·s^-1)比一般文献值高,其原因：一是水在油相中有较大的溶解度;二是渗滤现象的存在,由于液滴间相互作用的增强和：粘性“碰撞而导致液滴的融合,以及由此而形成的瞬时水相连续通道,使水的自扩散系数增大。而辛烷自扩散系数比一般文献值小,则是由于在微乳液液滴的栅栏中表面活性剂分子烃链与辛烷分子间范德华引力所造成。     

Significant immunological cross-reactivity of plant glycoproteins

Plant glycoproteins generally cross-react because of the presence of identical or related complex glycans which are highly immunogenic. The use of mild periodate oxidation of glycans after glycoprotein transfer from sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels to nitrocellulose membranes prior to immunodetection is a way of identifying the carbohydrate antigenic determinants of a glycoprotein as the basis for antigenic cross-reaction. Periodate oxidation can distinguish between antibodies directed against carbohydrate and against peptide antigenic determinants, the latter being unaffected by oxidation. Immunoblotting performed after periodate treatment allows the detection of common protein epitopes.     

Ti掺杂对α″-Fe16N2相稳定性的影响

研究了掺杂Ti对α″-Fe₁₆N₂相稳定性的影响，发现适量Ti掺杂有利于α″-Fe₁₆N₂相的形成．理论分析表明，掺杂适量Ti元素后含Ti的α″-(Fe,Ti)₁₆N₂相的生成焓降低，使α″相的稳定性提高，也使α″相更易制备．Ti浓度为3—15at％的(FeTi)-N薄膜具有高饱和磁化强度，μ₀M_s=2.3—2.5T． 关键词：     

Synthesis of novel benzoxathiazepine-1,1-dioxides by means of a one-pot multicomponent reaction

A simple one-pot synthesis of benzoxathiazepine-1,1-dioxides is described. Increased yields are afforded when suitable substituents are present in one of the starting materials. These additional substituents also provide a handle for further functionalization.     

Azide addition to an endohedral metallofullerene: formation of azafulleroids of Sc3N@I(h)-C80

The reaction of an organic azide with an endohedral metallofullerene has been investigated for the first time. Isomeric [5,6]- and [6,6]-azafulleroids can be obtained from the thermal reaction of Sc(3)N@I(h)-C(80) with 4-isopropoxyphenyl azide, while photoirradiation leads exclusively to the [6,6]-azafulleroid. An unprecedented thermal interconversion between the two isomeric azafulleroids has also been discovered.