Intensive leak standards for helium leak detection

The article discusses the main reasons for the demand for gas leak standards with a flow range of 5⋅10-7 to 5⋅10-4 Pa⋅m3/s, for helium leak detection. The high flow Leak Standards Vactron VKT are presented.

Plugging mechanisms of polymer gel used for hydraulic fracture water shutoff

The performance of polymer gel to plug a hydraulic fracture is greatly affected by its distribution patterns and gelling effect. In this study, the migration of a gel plugging agent in a fracture and its plugging after gelling were investigated by physical simulation experiments. In addition, the distribution patterns of the gel plugging agent and its plugging mechanism after gelling were investigated in detail. The results of this study revealed that the migration flowing behavior of the gel solution in a fracture can be divided into three streams: fracture flow, leak off flow, and matrix flow. Such behavior distributed the gel in three different patterns after gelling: gel clusters in the fracture, gel layer on the fracture surface, and dispersed gel lumps in the matrix pores-throats. Because of the leak off flow and the difference in components, the gel solution has apparent disproportional leak off–diffusion of components during its migration in a fracture, with less polymer molecules and loss of more cross-linking agent ions. The leak off of the cross-linking agent significantly deteriorates the gelling strength of the polymer gel, affecting its performance to plug a hydraulic fracture. The results also show that when the normalized concentration of the cross-linking agent ions in a fracture is less than 0.6, gel fails to plug the fracture effectively after gelling. When gelling was carried out by in situ cross-linking, polymer gel provided more satisfactory plugging performance than the gelling via ground pre-cross-linking.

Use of Color Flow Doppler Ultrasonography to Increase the Safety of Intrathecal Drug Delivery System Refills

Intrathecal drug delivery systems are effective tools in the treatment of chronic pain or spasticity. Using intrathecal drug delivery systems, drugs are directly infused into the cerebrospinal fluid and gain access to critical receptors in the central nervous system. This delivery method allows for the use of markedly reduced doses of medications to produce the same effects as seen with higher orally administered doses. Reduced dosing produces fewer side effects, creating a more favorable treatment course for patients already suffering from chronic pain or spasticity. Complications with intrathecal drug delivery systems can occur during both the implantation process and the postoperative maintenance of the device. The most common procedure carried out during postoperative maintenance of these devices is the intrathecal pump refill. This procedure must be performed by experienced practitioners in a systematic way in order to prevent complications. The most dreaded of these complications is inadvertent injection of medication into the subcutaneous space as opposed to into the device, commonly referred to as a “pocket fill.” This paper describes and recommends the routine use of color flow doppler ultrasonography as an easy, safe, and effective tool to reduce the chance of a catastrophic “pocket fill.” Routine utilization of live color flow ultrasound guidance during pump refills allows the practitioner to carefully document flow of medication into the pump under the silicone septum. It also allows for demonstration of no leakage from, or fluid increase superficial to, the septum. Additionally, 2 ultrasound images are obtained to document color flow deep to the septum and no color flow/leak/fluid superficial to the septum. Although this complication is rare, it can lead to severe complications including oversedation, respiratory depression, and death. As such, we believe that the utilization of color phase doppler ultrasonography could further reduce this incidence. Key words: Analgesics, opioids, chronic pain, drug overdose, infusion pumps, implantable, injections, spinal, medication errors, spasticity, ultrasonics, methods, ultrasonography, interventional

Genderqueer(ing): ‘On this side of the world against which it protests’

Deconstructionism as a method in transgender studies has been useful to collapse concepts and ideas about (trans) gender and sexuality. In spite of the usefulness of undoing the gender and sexuality canon, by way of concentrating on transgender practices, the resulting deconstructions often leave us with no place to go. This article develops an analysis of transsexual and genderqueer people’s bodily aesthetic assemblages, challenging theorizations that exclusively pit transsexual people as subjugated and genderqueer people as subversive. Drawing on interview data from 23 transsexual and genderqueer people, this article argues that transsexual and genderqueer people, regardless of their desire for particular bodily aesthetic interventions and gender recognition, productively flee, elude, flow, leak and disappear from categorizing legal statutes and healthcare protocols. The article concludes by arguing that deconstructive work becomes divisive and unproductive for theorizing and understanding the bodily aesthetics and diverse connectivities and affectivities of transsexual and genderqueer people, all of whom become territorialized, deterritorialized and reterritorialized through polyvocal bodily aesthetic assemblages.

Stent Graft-in-Stent Graft as a Rescue Technique for Endovascular Treatment of Giant Extracranial Internal Carotid Aneurysm

Endovascular treatment of a giant extracranial internal carotid aneurysm by a stent graft implantation was unsuccessful due to a high flow leak directly through the stent graft’s coating. The problem was solved deploying a second stent graft inside the previously implanted one resulting in complete exclusion of the aneurysmal sac and patent carotid lumen preservation. The review of the literature did not provide a case using this endovascular strategy. Follow-up for more than 12 months, using CT angiography, showed confirmed aneurysmal exclusion and carotid patency and no clinical complications have been detected.

Rarefied gas flow in pressure and vacuum measurements

Flows of a gas through the piston-cylinder gap of a gas-operated pressure balance and in a general vacuum system have one aspect in common, namely that the gas is rarefied due, respectively, to the small dimensions and the low pressure. The flows in both systems could be characterised as being in either slip-flow or transition regimes. Therefore, fundamental research of flow in these regimes is useful for both pressure and vacuum metrology, especially for the gas-operated pressure balance where a continuum viscous flow model is widely used for determining the effective area of the pressure balance. The consideration of gas flow using the most suitable assumption would improve the accuracy of such a calculation. Moreover, knowledge about rarefied gas flow will enable gas behaviour in vacuum and low-flow leak detection systems to be predicted. This paper provides useful information about rarefied gas flow in both slip-flow and transition regimes.

Environmental Study with Analysis the Characteristics and Safety Distance of LPG Pool Fires

In order to study the characteristics and the safe distance of LPG pool fires, a modeling of the pressure leaked from storage tanks, and the fire characteristic parameter calculation model, and thermal radiation intensity prediction model for LPG pool fire, and for liquid flow leak pool fire case, using MATLAB software programming, obtained characteristics parameters of LPG pool fire and damage assessment, analyzed the effects of a cross wind on the flame size and shape and the thermal radiation, put forward a calculation method of the LPG pool fire safe distance, provide guidance for the fire tactics equation of safety equipment and storage tank area configuration.