Current Injectors Research Articles

Relationship between opioid cross-tolerance during buprenorphine stabilization and return to opioid use during buprenorphine dose tapering.

Opioid injection drug use (IDU) has been linked to a more severe pattern of use (e.g. tolerance, overdose risk) and shorter retention in treatment, which may undermine abstinence attempts. This secondary data analysis of four human laboratory studies investigated whether current opioid IDU modulates subjective abuse liability responses to high-dose hydromorphone during intermediate-dose buprenorphine stabilization (designed to suppress withdrawal but allow surmountable agonist effects), and whether hydromorphone response magnitude predicts latency of return to opioid use during buprenorphine dose-tapering. Regular heroin users not currently seeking treatment (n = 54; 29 current injectors, 25 non-injectors) were stabilized on 8-mg/day sublingual buprenorphine and assessed for subjective responses (e.g. 'liking', craving) to hydromorphone 24-mg intramuscular challenge (administered 16-hr post-buprenorphine) under randomized, double-blinded, controlled conditions. A subgroup (n = 35) subsequently completed a standardized 3-week outpatient buprenorphine dose-taper, paired with opioid-abstinent contingent reinforcement, and were assessed for return to opioid use based on thrice-weekly urinalysis and self-report. During buprenorphine stabilization, IDU reported lower 'liking' of buprenorphine and post-hydromorphone peak 'liking', 'good effect' and 'high' compared to non-IDU. Less hydromorphone peak increase-from-baseline in 'liking' (which correlated with less hydromorphone-induced craving suppression) predicted significantly faster return to opioid use during buprenorphine dose-tapering. In these buprenorphine-stabilized regular heroin users, IDU is associated with attenuated 'liking' response (more cross-tolerance) to buprenorphine and to high-dose hydromorphone challenge and, in turn, this cross-tolerance (but not IDU) predicts faster return to opioid use. Further research should examine mechanisms that link cross-tolerance to treatment response.

A Novel Ferroelectric Rashba Semiconductor.

Fast, reversible, and low-power manipulation of the spin texture is crucial for next generation spintronic devices like non-volatile bipolar memories, switchable spin current injectors or spin field effect transistors. Ferroelectric Rashba semiconductors (FERSC) are the ideal class of materials for the realization of such devices. Their ferroelectric character enables an electronic control of the Rashba-type spin texture by means of the reversible and switchable polarization. Yet, only very few materials are established to belong to this class of multifunctional materials. Here, Pb1- xGexTe is unraveled as a novel FERSC system down to nanoscale. The ferroelectric phase transition and concomitant lattice distortion are demonstrated by temperature dependent X-ray diffraction, and their effect on electronic properties are measured by angle-resolved photoemission spectroscopy. In few nanometer-thick epitaxial heterostructures, a large Rashba spin-splitting is exhibiting a wide tuning range as a function of temperature and Ge content. This work defines Pb1- xGexTe as a high-potential FERSC system for spintronic applications.

Adapted "Break the Cycle for Avant Garde" intervention to reduce injection assisting and promoting behaviours in people who inject drugs in Tallinn, Estonia: A pre- post trial.

In the context of established and emerging injection drug use epidemics, there is a need to prevent and avert injection drug use. We tested the hypothesis that an individual motivation and skills building counselling, adapted and enhanced from Hunt's Break the Cycle intervention targeting persons currently injecting drugs would lead to reduction in injection initiation-related behaviours among PWID in Tallinn, Estonia. For this quasi-experimental study, pre-post outcome measures included self-reported promoting behaviours (speaking positively about injecting to non-injectors, injecting in front of non-injectors, offering to give a first injection) and injection initiation behaviours (assisting with or giving a first injection) during the previous 6 months. Of 214 PWID recruited, 189 were retained (88.3%) for the follow-up at 6 months. The proportion of those who had injected in front of non-PWID significantly declined from 15.9% to 8.5%, and reporting assisting with 1st injection from 6.4% to 1.06%. Of the current injectors retained in the study, 17.5% reported not injecting drugs at the follow up. The intervention adapted for the use in the setting of high prevalence of HIV and relatively low prevalence of injection assisting, tested proved to be effective and safe.

Transition metals doped (3,3) armchair boron nitride nanosheet as dilute magnetic semiconductors materials for the spintronic application

AbstractMagnetic 2D materials have attracted considerable attention for their significant potential application in spintronic. In this work, the effect of substitutional doping of 3d‐transition metals such as Co, Cr, Mn, and Fe on the magnetic and electronic properties of boron nitride nanosheet (BNNS) was studied based on the spin‐polarized density functional theory. The results revealed that the non‐magnetic and semiconducting behavior of BNNS can be altered by magnetically active dopants. The spin‐polarized density of states suggests that pure BNNS is a nonmagnetic semiconductor with a direct bandgap while transition metals doped BNNS are dilute magnetic semiconductors or half metals (HM). Co doping shows the most stable ferromagnetic phases in the nanosheet. A pair of Mn and Co atoms doped BNNS in edge structure show HM property with 100% spin polarization and seem to be good candidates for spintronic applications and especially as spin filter devices and spin current injectors.

Electromigration Performance Improvement of Metal Heaters for Si Photonic Ring Modulators

Ring-based, resonant Si photonic (SiPho) devices are temperature sensitive and require thermal tuning for stable operation, which is accomplished with integrated metallic heaters. This paper investigates the combined electromigration (EM) and thermal performance of tungsten (W) heaters using calibrated electro-thermal finite element models. The current injectors that are used to supply the current to the heater are a known weak spot for electromigration. The presented modelling study shows the conflicting design requirements for optimal thermal performance and optimal EM performance, which results in the need of a careful trade-off, supported by experimental reliability data. Based on modelling results, new device designs are proposed with significant performance increase. Lastly, a new methodology is introduced which allows to predict the lifetime of the W-heaters, given specific operating conditions such as ambient temperature and required phase shift.

Terahertz difference-frequency-generation quantum cascade lasers on silicon with wire grid current injectors.

We propose the concept and experimentally verify the operation of terahertz quantum cascade laser sources based on intra-cavity Cherenkov difference-frequency generation on a silicon substrate with the current injection layer configured as a metal wire grid. Such a current injector configuration enables high transmission of TM-polarized terahertz radiation into the silicon substrate while simultaneously providing a low-resistivity metal contact for current injection.

Neural Reflex Networks for Automating Quadcopter Drone Obstacle Avoidance

The physically modelled neural and nervous networks pioneered more than two decades ago by Mark Tilden, E. A. Rietman and collaborators, M. Ashkenazi et al. have proven to be a robust and interesting way to obtain powerful emergent behavior by utilizing neuromimetic circuitry. Using a physical representation of biologic neurons, both motor (NU) and cortical (NV) these structures mimic simple reflex arcs present in a large number of evolved organisms. The simple circuits using logic gate oscillators wired as integrators or pulse delay loops with sensors coupled as current injectors or variable resistors of different types demonstrated unexpected emergent „survival” behaviors when connected in chains or loops of several neurons. Mark Tilden calls the simplest functional unit of such looped structures „bicores”-as two neurons linked together in a loop already generate meaningful behavior when their inputs are linked to appropriate sensors. These powerful neuromimetic machines allow for a robust implementation of automated responses in autonomous or semi-autonomous robots. Quadcopters are a very good target for neural network control/stabilization because of their unique flight dynamics and normal control procedures. Obstacle avoidance and stabilization are simple tasks for a well-tuned physical neural network.

Experiment methods and apparatus for finely controlled partial needle lift measurements with a gasoline direct injector

In this study, an experiment method and apparatus are developed which allow exploration of partial-lift spray in a production gasoline direct injection (GDI) injector. For this injector, discretizing the needle’s stroke into a series of steady partial-lift tests seems a viable approach for quantifying transient behavior, where spray performance is often inferior from the perspective of emissions. However, performing such tests is not trivial due to manufacturing challenges and material limitations making it difficult to isolate any particular lift at pressure. To explore the applicability of fixed partial-lift tests, the following are performed: (1) An inward-opening multi-hole GDI injector is minimally modified with an apparatus to finely control needle lift by limiting the needle’s stroke with a fine micrometer head. (2) An experiment process is developed to associate the micrometer set-point with the imposed needle lift, compensating for pressure induced component flex. This flex is significant and of a similar magnitude to the needle’s stroke. (3) In-nozzle flow is simulated using computational fluid dynamics (CFD) within the AVL FIRE software to compare a stationary and moving needle. The comparison reveals a relative insignificance of needle velocity for the majority of the needle’s stroke (>5 μm). The nozzle hole flow rates and effective exit velocities are similar, suggesting fixed partial-lift spray well approximates the normally moving needle spray. This new experiment method can be used on current injectors to quantify spray performance during needle transients by discretizing the stroke into steps as small as 2 μm, exceeding the control in any current published literature.

Optimizing the geometry of aerodynamic lens injectors for single-particle coherent diffractive imaging of gold nanoparticles.

Single-particle X-ray diffractive imaging (SPI) of small (bio-)nanoparticles (NPs) requires optimized injectors to collect sufficient diffraction patterns to allow for the reconstruction of the NP structure with high resolution. Typically, aerodynamic lens-stack injectors are used for NP injection. However, current injectors were developed for larger NPs (>100 nm), and their ability to generate high-density NP beams suffers with decreasing NP size. Here, an aerodynamic lens-stack injector with variable geometry and a geometry-optimization procedure are presented. The optimization for 50 nm gold-NP (AuNP) injection using a numerical-simulation infrastructure capable of calculating the carrier-gas flow and the particle trajectories through the injector is also introduced. The simulations were experimentally validated using spherical AuNPs and sucrose NPs. In addition, the optimized injector was compared with the standard-installation 'Uppsala injector' for AuNPs. Results for these heavy particles showed a shift in the particle-beam focus position rather than a change in beam size, which results in a lower gas background for the optimized injector. Optimized aerodynamic lens-stack injectors will allow one to increase NP beam density, reduce the gas background, discover the limits of current injectors and contribute to structure determination of small NPs using SPI.

Experimental proof test of CW mode RF modulated grid-controlled thermionic electron gun

A CW mode RF modulated grid-controlled thermionic electron gun was proposed by Institute of Modern Physics (IMP), Chinese Academy of Sciences (CAS) for some high average current electron accelerators requirements. The RF modulated grid-controlled thermionic electron gun was selected for these purposes due to its simplicity and cost savings. The experimental proof test of this type electron gun was conducted. The RF power supply at 107.5 MHz for the grid modulation can be adjusted from 10 W to 70 W. The RF power is coupled into the gun of grid-cathode through a RF&DC modulator. The electromagnetic field and RF simulation of the modulator is presented here. The gun structure and the beam dynamics design are also shown in the paper. The cathode assembly and the electron guns are tested on a 10 kV test bench for beam characterization. The CW mode 107.5 MHz electron beam obtained from the proof test, which is important for future high average current electron injectors development.

Initial characterization of electron temperature and density profiles in PEGASUS spherical tokamak discharges driven solely by local helicity injection

Local helicity injection (LHI) is a non-solenoidal startup technique that utilizes electron current injectors at the plasma edge to initiate tokamak discharges. Viable non-solenoidal startup techniques require high central Te to combat resistive losses and enhance coupling to auxiliary methods of current drive/heating. Thomson scattering measurements of LHI discharges in Pegasus showed peaked Te profiles at Ip∼0.15 MA and Bt∼0.15 T with Te,0∼100– 150 eV. These results are similar to Te profiles observed with Ohmic induction. At lower levels of Bt, LHI Te profiles were hollow with Te,0∼40 eV and Te,max≤120 eV depending upon the helicity input. Regardless of the Bt level and helicity input, the electron pressure profiles were flat/peaked with hollow JR profiles. Equilibrium reconstructions and measurements of core absolute extreme ultraviolet radiation suggest the hollow Te profiles are a result of very low resistive heating power in the core due to the edge-localized nature of LHI and low-Z line radiation losses. Estimates of Zeff from the plasma conductivity indicate averaged values of ∼1 or ∼3 assuming neoclassical or Spitzer conductivity, respectively. When auxiliary heating power from magnetic reconnection is considered, this observed LHI performance is comparable to expectations from a linear Ohmic confinement scaling estimate and a collisional stochastic confinement scaling estimate of the core plasma region.

Negligible spin–charge conversion in Bi films and Bi/Ag(Cu) bilayers

Spin pumping experiments using ferromagnetic metals have reported highly efficient spin–charge conversion in Bi and at the Bi/Ag interface, possibly due to the inverse Rashba–Edelstein effect. However, longitudinal spin Seebeck effect experiments using the yttrium iron garnet ferrimagnetic insulator in Bi films and Bi/Ag bilayers do not show evidence of appreciable spin-to-charge conversion except the large Nernst signal inherent to Bi. These contrasting conclusions highlight the differences between magnetic metals and magnetic insulators as spin current injectors. Only the detected voltages that adhere to the inverse spin Hall effect of jC = (2e/ℏ)θSH jS × σ are due to spin currents.

Risk factors for leg ulceration in people who inject drugs: A cross‐sectional study

The aim of this study was to assess, for the first time in a hard-to-reach population, the risk factors for leg ulceration among PWID, with the objective of making improvements to prevention and care. An estimated 4.8 million people globally inject drugs with potential for injecting-related harm. Skin and vein damage associated with drug injecting is increasing. Leg ulceration is a chronic condition which in the UK has a prevalence of 15% among people who have injected drugs (PWID) compared with 1% in the general population. Glasgow has the highest rate of problematic drug use in Scotland with approximately 13,900 individuals, about 50% of whom are thought to inject. However, the reasons for high prevalence of leg ulceration among PWID are unknown. To support improvements in prevention and care, the dearth of evidence around risk factors for leg ulceration in PWID needs to be addressed. A cross-sectional survey of 200 current and former injectors recruited from drug services in Glasgow, Scotland, to measure skin problems, leg ulceration and injecting habits is reported following STROBE guidelines. Logistic regression modelling examined whether demographics and injecting habits predicted leg ulceration. The likelihood of leg ulceration was increased for those who injected in the groin and the leg. Additionally, injecting in the groin and leg were associated with having a DVT. The primary risk factors for leg ulceration in PWID are injecting in the groin and the legs and these are clinically linked to deep vein thrombosis. Injecting into the femoral vein is increasingly common practice for PWID and healthcare practitioners should advise injectors of the increased risk of leg ulceration and DVT and discourage injecting into these areas.

Repetitive regime of highly focused liquid microjets for needle-free injection

Fast liquid jets are investigated for use as a needle-free drug delivery system into an elastic tissue such as skin. Using smaller jet diameters in a repetitive regime can mitigate bruising and pain associated with current injectors. In this study, we aim to unravel the potential of the method to deliver liquids into biological tissues having higher elasticity than healthy skin (i.e >60 kPa). To address this challenge, we have implemented a laser-based jetting system capable of generating supersonic liquid microjets in a repetitive regime. We provide insights on the penetration of microjets into hydrogel samples with elastic modulus ranging from 16 kPa to 0.5 MPa. The unprecedented speeds of injection (>680 m/s) together with a newly introduced repetitive regime opens possibilities for usage in needle-free drug administration into materials with elasticity covering the wide spectrum of biological soft tissues like blood vessels, all skin layers, scarred or dried skin or tumors.

Unique Infill Configuration To Unlock Additional Barrels in the Boscán Heavy-Oil Water-Injection Project

Summary Boscán is a giant multibillion-barrel heavy-oil (10.5 °API and asphaltic) field in Venezuela. Although a large part of the field is on primary production with a low recovery factor (<6%), water injection has been successfully implemented in portions of the field for more than 15 years, with improved recovery. High-mobility-ratio-waterflood (HMRWF) behavior and associated key production mechanisms obtained from detailed field-data analysis and dynamic modeling are presented. A novel and unique infill configuration is also proposed to further improve recovery in this environment with a high (or adverse) mobility ratio. Water injection in such heavy oil was previously considered not effective by the industry because of adverse mobility ratio. However, water injection for pressure maintenance (WIPM) was successfully implemented using a new pattern configuration, a pseudo-1-3-1 inverted- spot pattern (an additional row of producers between conventional-pattern rows). Field-data and reservoir-simulation models show increased reservoir pressure up to the second row of producers from the injector. The pressure support is used to significantly improve recovery using the unique configuration at low water cut. WIPM has already resulted in significant reserves addition. Current production from water-injection areas is approximately 40,000 MBOPD (or approximately 47% of field production). However, it is estimated that because of high oil viscosity, a significant amount of oil remains bypassed in the WIPM area. An infill opportunity was identified from an integrated reservoir-management study that included detailed WIPM data analysis and dynamic (mechanistic and full-field) modeling. A unique infill configuration is proposed that conceptually uses the current injectors with an additional row of producers between the existing first and second row of the producers. This configuration has the potential to economically unlock millions of barrels of bypassed oil and significantly increase recovery in this prolific heavy-oil field. This study provides insights into HMRWF behavior, evaluating the relative effect of displacement vs. pressure. The unique and novel infill configuration can be used to improve recovery, a step vital to monetize this large resource in the low-price environment.

Perceived Causes of Personal versus Witnessed Overdoses among People who Inject Opioids

Background: Studies show that people who inject drugs (PWID) underestimate their overdose risk. We sought to explore this phenomenon by comparing how PWID perceive causes of personal overdoses compared to witnessed overdoses. Methods: We analyzed 40 interviews from participants enrolled in a randomized-controlled behavioral intervention to reduce overdose among at-risk PWID in San Francisco from 2014 to 2016. Subjects were current illicit opioid injectors with opioid use disorder, had received take-home naloxone, and had overdosed within five years. Interviews were audio-recorded and transcribed verbatim. Using thematic content analysis, three analysts coded the interviews and measured interrater reliability. The analysts developed a codebook of a priori and inductively generated codes, and applied it to all interviews. Coding discrepancies were discussed. Results: We used two theoretical frameworks – actor observer bias (AOB) and intragroup stigma – to analyze participants’ descriptions of personal and witnessed overdoses. AOB suggests individuals may assign responsibility of their actions to external factors, while assigning responsibility for others’ actions to internal mechanisms. Intragroup stigma describes the process whereby people perpetuate stigma within their own group. Related to these concepts, two principal themes were used to describe personal overdose: (1) drug volatility and (2) ascribing blame to others, and witnessed overdoses: (1) greed and (2) inexperience/foolishness. Conclusion/Importance: The differences in perceived causes of personal versus witnessed overdose align with AOB and intragroup stigma. Understanding how these theories shape overdose experiences may improve behavioral interventions by introducing peer based supports and encouraging PWIDs to employ evidence-based safety precautions when using opioids.Trial registration: ClinicalTrials.gov identifier: NCT02093559.

Rapid reconstitution packages (RRPs) for stable storage and delivery of glucagon.

Current emergency injectors of glucagon require manual reconstitution, which involves several steps that may lead to dosage errors. Rapid reconstitution packages (RRPs) are new devices, designed using computational fluid dynamics (CFD) to optimize fluid mixing, integrating physical properties of active pharmaceutical ingredients (APIs), excipients and diluents. RRPs improve drug stability for long-term storage and ease of delivery. Device prototypes were manufactured using advanced stereolithography apparatus (SLA) 3D printing technology. Reconstitution of glucagon with RRPs was evaluated by high-performance liquid chromatography (HPLC) and optical spectroscopy methods. Enzyme-linked immunosorbent assays were performed to test in vitro activity. Experimental results showed that RRPs effectively reconstituted glucagon even after exposure to 60°C for a 24-h period. RRPs exhibited improved performance at maintaining drug stability compared to lyophilized glucagon stored in a standard glass vial under the same temperature conditions. RRPs represent a portable platform for rapid reconstitution of lyophilized drugs, compatible with standard syringes available in any clinical setting. The RRP provides an alternative to manual reconstitution process, especially designed for medical emergencies.

Magnetic hallmarks of viscous electron flow in graphene

We propose a protocol to identify spatial hallmarks of viscous electron flow in graphene and other two-dimensional viscous electron fluids. We predict that the profile of the magnetic field generated by hydrodynamic electron currents flowing in confined geometries displays unambiguous features linked to whirlpools and backflow near current injectors. We also show that the same profile sheds light on the nature of the boundary conditions describing friction exerted on the electron fluid by the edges of the sample. Our predictions are within reach of vector magnetometry based on nitrogen-vacancy centers embedded in a diamond slab mounted onto a graphene layer.

A qualitative study of persons who inject drugs but who have never helped others with first injections: how their views on helping contrast with the views of persons who have helped with first injections, and implications for interventions

BackgroundTransitioning from non-injection to injection drug use dramatically escalates health risks. Evidence suggests that people who inject drugs (PWID) help in a majority of others’ first injections, yet these helpers represent only a minority of experienced PWID. Recent research has provided insight into this helping process, as reported by helpers. PWID who have never helped, although the majority of PWID, have not previously been the focus of study. To address this gap, we give primary voice to non-helpers’ perspectives on the helping process, while also comparing their views with persons in our sample who have helped with first injections. Finally, we consider how non-helpers’ perspectives can inform harm reduction interventions to reduce, or make safer, initiation into injecting drug use.MethodsWe conducted audio-recorded, qualitative interviews with 23 current opioid injectors on Staten Island, NY, where the opioid epidemic is pronounced. Seventeen had never helped with first injections and 6 had. Interviews were transcribed verbatim, and three coders used a consensus-developed codebook to code all interviews. Framework analysis was used to identify overarching themes.ResultsWe identified three key themes in non-helpers’ discourse around not helping: altruistic motivations to prevent immediate and delayed harms to individuals injecting for the first time; inhibition due to negative assessments of their own injecting skills; and absolutist ethical convictions against helping. Non-helpers differed from helpers on each theme.ConclusionsBecause most PWID have never helped with first injections, their perspectives on helping warrant consideration and can inform harm reduction interventions to reduce, or make safer, transitions to injection drug use. Their perspectives can be used to broaden the factors PWID consider around questions of promoting injection and helping with others’ first injections, including considerations of the moral issues involved in choosing to help or not to help.

Achieving a hepatitis C cure: a qualitative exploration of the experiences and meanings of achieving a hepatitis C cure using the direct acting antivirals in Australia

BackgroundUniversal access to the hepatitis C direct acting antiviral (DAAs) regimens presents a unique opportunity to eliminate hepatitis C in Australia. Large numbers of Australians have already been cured using these treatments, however, the numbers presenting for treatment have begun to plateau. This study explored how people experienced and understood being cured of hepatitis C, with the aim of informing interventions to increase uptake of DAA treatment among people with hepatitis C.MethodsThis qualitative study used semi-structured interviews to explore the experiences of people with hepatitis C taking DAAs accessing both hospital and community clinics. Interviews were conducted 12 weeks after treatment completion. Participants were asked to reflect on their experience of living with hepatitis C, their reasons for seeking treatment, and their experience of, DAA treatments. Participants were also asked to reflect on the meaning of being cured, and how they shared this experience with their peers. Interviews were transcribed verbatim and key themes were identified using inductive thematic analysis.ResultsTwenty participants were interviewed. While participants described a range of physical health benefits of achieving a hepatitis C cure it was an improved sense of psychological wellbeing that had the most significant impact on participants’ lives. The majority described their relief about no longer living with the burden of an uncertain future due to anxiety about developing liver disease or cancer, as well as fear of infecting others. Participants who had a past history of injecting drug use, described being cured as a way to break the connection with their past. Participants who were current injectors raised concerns about re-infection.ConclusionFeeling “normal” and not infectious allows people to live with reduced psychological distress, in addition to the physical benefits of no longer being at risk of developing serious liver disease. Future engagement strategies targeting people who are not accessing hepatitis health care need to promote the lived experience of being cured and the substantial psychological, and physical health benefits, offered by achieving a cure. Interventions aimed at people who are currently injecting also need to highlight the availability of re-treatment in conjunction with primary prevention strategies.