Standard Injection Technique Research Articles

Monte Carlo calculations of base transit time in bipolar transistors

Previous analytical treatments of low-field electron transport in the base of bipolar transistors have all made the implicit assumption that the velocity distributions are Gaussian. Using material and scattering parameters appropriate to GaAs and a simple model for the transistor base in which the collector is replaced by a step potential, we have found that near the collector these distributions are distorted, leading to a diffusion velocity exceeding the thermal velocity. We also investigated the effects of the base-emitter boundary condition and found that standard injection techniques can force non-equilibrium distributions. This becomes critical as the base lengths become sub-micron and boundary effects dominate. With use of a dead region, where the electron distributions could relax before injection, to overcome this problem we found close agreement with the analytical results of Herbert.

Is the use of intraoperative post-reconstruction angiography following in situ saphenous vein bypass redundant?

The value of post-reconstruction intraoperative angiography after in situ saphenous vein bypass has not been clearly defined. A retrospective review of intraoperative completion angiography using a standard proximal bypass injection technique without inflow occlusion was performed on 298 in situ saphenous vein bypasses constructed over a 72-month interval to treat critically ischemic limbs. Abnormal operative angiograms were found on retrospective review in 55 cases (18%). Minor abnormalities such as distal arterial or vein conduit spasm (class I defects) were found in 26 bypasses (9%) and required no surgical intervention. An anastomotic buckle or extrinsic compression due to an adventitial band (class II defect) was seen in five bypasses (2%). Defects requiring a major surgical revision (class III) were seen in 24 instances (8%). These abnormalities included nine cases with intraluminal platelet thrombus and six with a significant anastomotic torsional abnormality. In addition, there were five bypasses anastomosed to unsuitable diseased segments of distal arteries. Three of 24 (12%) of the bypasses with class III angiographic abnormalities required further revision within the first month after surgery, after duplex scanning had identified hemodynamically significant abnormalities, compared with 14 of 274 (5%) early revisions of the remaining in situ bypasses. The 30-day primary patency rate for bypasses with class III angiographic abnormalities was 88%. This compares with a rate of 95% for the remaining bypasses. The difference was not statistically significant. The 30-day and 48-month secondary patency rates for bypasses undergoing an immediate intraoperative revision for a class III abnormality were 100% and 93%, respectively. These rates were equivalent to the secondary patency of the in situ bypasses without class III abnormalities. Although the incidence of significant (class II and class III) angiographic abnormalities was low (10%), these abnormal findings allowed immediate correction of a jeopardized bypass, with minimal sequelae.

A new vascularized bone graft for scaphoid nonunion

Nonunion and avascular necrosis after scaphoid fractures continue to be problem sequelae because of unrecognized injuries, inadequate immobilization techniques, or insufficient treatment time. Screw fixation and inlay bone grafting techniques remain the options of choice, with successful union reported in approximately 90% of patients. However, prolonged immobilization with plaster up to 4 to 6 months is required with conventional techniques. With the use of standard latex injection techniques with vascular filling of vessels to less than 0.1 mm diameter in ten fresh cadaver dissections, we discovered a consistent vascularized bone graft source from the distal dorsoradial radius. We have used this vascularized bone graft source with good results in eleven patients with long-standing nonunion of the scaphoid. It is technically easy and seemingly offers the advantages of a decreased period of immobilization and a higher union rate.

Performance of an automated system for capillary microinjection into living cells

An automated capillary microinjection system for nuclear and cytoplasmic injections into cells is described. The system has been tested with samples of DNA, RNA and proteins. Movements of the capillary with precise cell positioning and time of injections are controlled by a computer. The first automated microinjection system allows injection of more than 1500 cells per hour with a minimum of practical training, volumes injected are more reproducible and cells are less damaged when compared with the standard manual injection technique. Retrieval of the injected cells is accurate to within 1% without complicated and laborius produced orientation marks on the cell support. The number of successfully injected cells is easily determined with great accuracy and the error of the statistical evaluation of the results is reduced to a minimum. Standardized procedures for pulling, handlin and storage of the injection capillaries were developed.

Rapid extraction and analysis of organic compounds from solid samples using coupled supercritical fluid extraction/gas chromatography

Direct coupling of supercritical fluid extractions with gas chromatography (SFE-GC) allows the extraction, concentration, and gas chromatographic analysis of organic analytes from solid samples to be performed in less than 1 h. Coupling of the supercritical fluid extraction step with a capillary gas chromatographic column is achieved using a standard on-column injector and requires no modification of the gas chromatograph. Maximum sensitivity is achieved and analyte degradation or loss is minimized since the extracted species are quantitatively transferred into the fusedsilica capillary gas chromatographic column where they are cryogenically focused prior to normal gas chromatographic analysis using flame ionization (SFE-GC/FID) or mass spectral (SFE-GC/MS) detection. SFE-GC analysis yields good chromatographic peak shapes that compare favorably with those obtained using standard on-column injection techniques. Class-selective extractions can be achieved by performing multiple SFE-GC analyses with different extraction pressures. The ability of coupled SFE-GC to yield rapid extraction and analysis of organic analytes is demonstrated for a variety of samples including polycyclic aromatic hydrocarbons (PAHs) from treated wood, urban dust, and river sediment, phenolic species from wood smoke particulates, nicotine from tobacco, biological markers from coal, and flavor components from food products.

Comparison of Intramuscular Injection Techniques to Reduce Site Discomfort and Lesions

The Z-track intramuscular injection technique was compared with the standard injection technique for incidence and severity of discomfort and lesions at the injection site. Fifty subjects received injections of meperidine hydrochloride alone or in combination with promethazine hydrochloride every 3 to 4 hours for a total of two to eight injections. Subjects served as their own controls by receiving both techniques. They were evaluated for the presence and severity of discomfort on a 4-point Likert scale. Injection site lesions were determined by visualization and palpation. The Z-track technique significantly decreased incidence of selected descriptors of discomfort and lesions at selected time intervals, severity of discomfort at selected time intervals, and severity of lesions at all time intervals postinjection.

An [formula omitted][formula omitted] cellular immune response to bacteria in the polychaete, [formula omitted][formula omitted] (L.) (Annelida)

The coelomocyte reactions of the marine polychaete, Arenicola marina (L.), in response to experimental infection have been investigated in vivo using standard injection and counting techniques with unlabelled and 14C-labelled bacteria, autoradiography and staining methods. In A. marina, 72% of the inoculum can be cleared within the first 20 min increasing to 92% by the first hour post-injection. These changes appear to be correlated with a reduction of free circulating coelomocytes and the appearance of cellular aggregates. These aggregates serve to contain the bacteria and many are eventually incorporated into ‘brown bodies’ which become necrotic and melanised. Coelomocytes enclosing ingested bacteria also migrate into many of the surrounding tissues.

Arrhythmias occurring during intravenous urography

A low but significant fatality rate persists in intravenous urography. Fatalities are sudden and their cause is not understood. This trial assessed the arrhythmogenic effects of a common urographic contrast agent. Using standard bolus injection techniques, 12 patients out of 58 (20%) developed post-injection arrhythmias. Seven of these cases (12%) were considered to have significant or potentially serious arrhythmias. This group includes various paroxysmal tachycardias and a case of atrioventricular block. Arrhythmia post-injection was commoner in the male and in the older age groups. An abnormal control ECG was not found to be a predisposing factor to the development of arrhythmia. It is suggested that the findings reflect the high incidence of latent coronary heart disease in our older male population. No correlation was found with minor side-effects of contrast injection and the development of arrhythmia.