Effect of Operating Conditions on the Gasification of Pet-Coke Water Slurry in an Entrained-Flow Gasifier Simulation.

Petroleum coke, commonly known as pet-coke, represents a promising and cost-effective alternative fuel source, produced as a byproduct of large-scale heavy crude oil refining. This study first simulated the gasification process of pet-coke slurry using a three-dimensional computational fluid dynamics (CFD) approach based on the Eulerian-Lagrangian method. The simulation was carried out in a 2-ton-per-day (2TPD) entrained-flow gasifier, aiming to optimize the production of hydrogen (H2) and carbon monoxide (CO) as synthetic gases. This study investigated the effects of operational parameters, including the oxygen/slurry ratio and moisture content in the slurry, on various aspects such as fluid dynamics, temperature distribution, particle trajectories, carbon conversion, and gas composition within the pet-coke slurry gasifier. The base conditions of the simulation were meticulously cross-validated with high-precision experimental data. The results indicated that higher oxygen/slurry ratios led to increased concentrations of carbon dioxide (CO2) and decreased fractions of H2, primarily due to the prevalence of the reverse water-gas shift reaction. Moreover, raising the moisture content in the pet-coke slurry led to decreased CO levels and enhanced production of H2 and CO2, triggered by the activation of the forward water-gas shift reaction. These results underscore the potential of pet-coke slurry as a favorable feedstock for syngas production and the achievement of carbon neutrality through the careful optimization of operational conditions. Our findings provide valuable insights for further experimental exploration and the development of practical applications for pet-coke gasification.

Tailored Self-Assembled Monolayer using Chemical Coupling for Indium-Gallium-Zinc Oxide Thin-Film Transistors: Multifunctional Copper Diffusion Barrier.

Controlling the contact properties of a copper (Cu) electrode is an important process for improving the performance of an amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistor (TFT) for high-speed applications, owing to the low resistance-capacitance product constant of Cu. One of the many challenges in Cu application to a-IGZO is inhibiting high diffusivity, which causes degradation in the performance of a-IGZO TFT by forming electron trap states. A self-assembled monolayer (SAM) can perfectly act as a Cu diffusion barrier (DB) and passivation layer that prevents moisture and oxygen, which can deteriorate the TFT on-off performance. However, traditional SAM materials have high contact resistance and low mechanical-adhesion properties. In this study, we demonstrate that tailoring the SAM using the chemical coupling method can enhance the electrical and mechanical properties of a-IGZO TFTs. The doping effects from the dipole moment of the tailored SAMs enhance the electrical properties of a-IGZO TFTs, resulting in a field-effect mobility of 13.87 cm2/V·s, an on-off ratio above 107, and a low contact resistance of 612 Ω. Because of the high electrical performance of tailored SAMs, they function as a Cu DB and a passivation layer. Moreover, a selectively tailored functional group can improve the adhesion properties between Cu and a-IGZO. These multifunctionally tailored SAMs can be a promising candidate for a very thin Cu DB in future electronic technology.

Delayed cauda equina syndrome by nerve root incarceration after caudal epidural block: A case report.

INTRODUCTION AND IMPORTANCE: Caudal epidural block has been commonly practiced in recent years and is used for management of pain before surgery and chronic back pain in adult spine diseases. CASE PRESENTATION: A 58-year-old man visited the outpatient clinic complaining of recently aggravated severe low back pain, saddle anesthesia, and unbearable radiating pain in his left leg, with a previous history of caudal epidural block. He had problems with bladder and bowel function. Emergency exploration for cauda equina syndrome (CES) was performed. Decompression, extradural herniation, and entrapment of a cauda equina filament through a dural defect were observed, and surgical reduction with dural repair was performed. CLINICAL DISCUSSION: The clinical signs at onset suggested cauda equina dysfunction after caudal epidural block. Magnetic resonance imaging showed spinal canal stenosis with a paracentral herniated intervertebral disc at the L4-L5 level without any other dural or nerve root abnormality. Exploration was the only option to identify the lesion. CONCLUSION: This is the first case report of CES caused by extradural nerve root herniation and strangulation after caudal epidural block.

Comparison of General and Spinal Anaesthesia on Systemic Inflammatory Response in Patients Undergoing Total Knee Arthroplasty: A Propensity Score Matching Analysis.

Background and Objectives: Some of the postoperative complications following orthopaedic surgeries are associated with a systemic inflammatory response (SIR), which varies depending on the anaesthetic technique. We aimed to compare the effects of general and spinal anaesthesia on the SIR after total knee arthroplasty (TKA), based on C-reactive protein (CRP) levels, the platelet-lymphocyte ratio (PLR), and the neutrophil-lymphocyte ratio (NLR). Materials and Methods: Patients who underwent TKA between January 2014 and December 2018 were included. Electronic medical records of the patients were retrospectively reviewed and analysed. To reduce the impact of potential confounding factors, we performed propensity score matching according to the anaesthetic technique. Results: A total of 1311 TKA cases were analysed. After propensity score matching, the maximal CRP value and changes in CRP levels in the general anaesthesia group were higher than those in the spinal anaesthesia group. However, the maximal NLR and PLR and the changes in NLR and PLR were not different between the two groups. There were no differences in postoperative clinical outcomes. Conclusion: Spinal anaesthesia tended to induce a lower inflammatory response than general anaesthesia when considering CRP levels in patients undergoing TKA. However, the effects of anaesthetic techniques on the overall outcomes were not significant.

Ultrasound-Guided Anterior Quadratus Lumborum Block Reduces Postoperative Opioid Consumption and Related Side Effects in Patients Undergoing Total Hip Replacement Arthroplasty: A Propensity Score-Matched Cohort Study.

Quadratus lumborum block (QLB) has been shown to be effective for pain relief after hip surgery. This study evaluated the efficacy of ultrasound-guided anterior QLB in pain control after total replacement hip arthroplasty (TRHA). A total of 115 patients receiving anterior QLB were propensity score-matched with 115 patients who did not receive the block. The primary outcome was opioid consumption at 24, 24-48, and 48 postoperative hours. Secondary outcomes included pain scores at the post-anesthesia care unit (PACU), 8, 16, 24, 32, 40, and 48 h length of hospital stay, time to first ambulation, and the incidence of opioid-related side effects. Postoperative opioid consumption 48 h after surgery was significantly lower in the QLB group. Resting, mean, worst, and the difference of resting pain scores compared with preoperative values were significantly lower in the QLB group during the 48 postoperative hours. The length of hospital stay was shorter in the QLB group. The incidence of postoperative nausea and vomiting was significantly lower in the QLB group during the 48 postoperative hours, except at the PACU. This study suggests that anterior QLB provides effective postoperative analgesia for patients undergoing THRA performed using the posterolateral approach.

Photo-induced Reactive Oxygen Species Activation for Amorphous Indium-Gallium-Zinc Oxide Thin-Film Transistors Using Sodium Hypochlorite.

We proposed a novel material named sodium hypochlorite (NaClO) solution as a source of activation for amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs). We reduced the activation temperature from 300 to 150 °C using NaClO solution (concentration: 50%) and obtained satisfactory electrical characteristics of a-IGZO TFTs. The field-effect mobility, threshold voltage, on/off ratio, subthreshold swing, and threshold voltage (Vth) shift under negative bias illumination stress (VG = -20 V and VD = 10.1 V for 10,000 s) of NaClO (50%)-activated a-IGZO TFTs were 10.41 cm2/V·s, 1.51 V, 2.78 × 108, 0.37 V/dec, and -5.43 V, respectively. Also, the Vth shifts of the NaClO (50%)-activated a-IGZO TFTs (150 °C) under the positive bias stress test decreased from 5.01 to 1.87 V (VG = 20 V and VD = 10.1 V for 10,000 s) compared with that of only-annealed (300 °C) a-IGZO TFTs. Also, the mechanism of NaClO activation for a-IGZO TFTs is clarified through photo-assisted oxygen radical (POR) and heat-driven oxygen radical (HOR) effects. The POR and HOR effects generated the reactive oxygen species (ROS) from NaClO solution (50%), which activated a-IGZO TFTs at a low temperature (150 °C). When the NaClO solution (50%) was exposed to external energy, it generated ROS such as hydroxyl radicals (OH•), hydroperoxyl radicals (HO2•), and oxygen radicals (O•), which promoted the formation of strong metal-oxide bonds in a-IGZO TFTs. Furthermore, NaClO solution (50%) was applied to a-IGZO TFTs on a flexible polyimide substrate and electrohydrodynamic printing process for selective deposition.

Low Psoas Lumbar Vertebral Index Is Associated with Mortality after Hip Fracture Surgery in Elderly Patients: A Retrospective Analysis.

The psoas-to-lumbar index (PLVI) has been reported as a simple and easy way to measure central sarcopenia. However, only few studies have evaluated the association between PLVI and survival in surgical patients. This study evaluated the association between preoperative PLVI and mortality in elderly patients who underwent hip fracture surgery. We retrospectively analyzed 615 patients who underwent hip fracture surgery between January 2014 and December 2018. The median value of each PLVI was calculated according to sex, and the patients were categorized into two groups on the basis of the median value (low PLVI group vs. high PLVI group). Cox regression analysis was performed to evaluate the risk factors for 1 year and overall mortalities. The median values of PLVI were 0.62 and 0.50 in men and women, respectively. In the Cox regression analysis, low PLVI was significantly associated with higher 1 year (hazard ratio (HR): 1.87, 95% confidence interval (CI): 1.18-2.96, p = 0.008) and overall mortalities (HR: 1.51, 95% CI: 1.12-2.03, p = 0.006). Low PLVI was significantly associated with a higher mortality. Therefore, PLVI might be an independent predictor of mortality in elderly patients undergoing hip fracture surgery.

Multifunctional Oxygen Scavenger Layer for High-Performance Oxide Thin-Film Transistors with Low-Temperature Processing.

In this study, the oxygen scavenger layer (OSL) is proposed as a back channel in the bilayer channel to enhance both the electrical characteristics and stability of an amorphous indium-gallium-zinc oxide thin-film transistor (a-IGZO TFT) and also to enable its fabrication at low temperature. The OSL is a hafnium (Hf)-doped a-IGZO channel layer deposited by radio-frequency magnetron cosputtering. Amorphous IGZO TFTs with the OSL, even if annealed at a low temperature (200 °C), exhibited improved electrical characteristics and stability under positive bias temperature stress (PBTS) compared to those without the OSL, specifically in terms of field-effect mobility (31.08 vs 9.25 cm2/V s), on/off current ratio (1.73 × 1010 vs 8.68 × 108), and subthreshold swing (0.32 vs 0.43 V/decade). The threshold voltage shift under PBTS at 50 °C for 10,000 s decreased from 9.22 to 2.31 V. These enhancements are attributed to Hf in the OSL, which absorbs oxygen ions from the a-IGZO front channel near the interface between a-IGZO and the OSL.

Vertically Graded Oxygen Deficiency for Improving Electrical Characteristics and Stability of Indium Gallium Zinc Oxide Thin-Film Transistors.

We investigated a facile fabrication method, which is an insertion of a carrier-induced interlayer (CII) between the oxygen-rich a-IGZO channel and the gate insulator to improve the electrical characteristics and stability of amorphous indium-gallium-zinc-oxide thin-film transistors (a-IGZO TFTs). The a-IGZO channel is deposited with additional oxygen gas flow during a-IGZO channel deposition to improve the stability of the a-IGZO TFTs. The CII is a less than 10 nm thick deposited thin film that acts to absorb the oxygen from the a-IGZO front channel through oxidation. Through oxidation of the CII, the oxygen concentration of the a-IGZO front channel is decreased compared to that of the oxygen-rich back channel, which forms a vertically graded oxygen deficiency (VGO) in the a-IGZO channel. Therefore, the electrical characteristics of the VGO TFTs are improved by increasing the carrier concentration of the front channel as the oxygen vacancy concentration in the front channel is increased through the oxidation of the CII. At the same time, the stability of the VGO TFTs is improved by maintaining a high oxygen concentration in the back channel even after oxidation of the CII. The field-effect mobility (µFET) of the VGO TFTs improved compared to that of the a-IGZO TFTs from 7.16 ± 0.6 to 12.0 ± 0.7 cm2/V·s. The threshold voltage (Vth) shifts under positive bias temperature stress and negative bias temperature illumination stress decreased from 6.00 to 2.95 V and -15.58 to -8.99 V, respectively.

Simultaneously Defined Semiconducting Channel Layer Using Electrohydrodynamic Jet Printing of a Passivation Layer for Oxide Thin-Film Transistors.

A simple fabrication method for homojunction-structured Al-doped indium-tin oxide (ITO) thin-film transistors (TFTs) using an electrohydrodynamic (EHD) jet-printed Al2O3 passivation layer with specific line (WAl2O3) is proposed. After EHD jet printing, the specific region of the ITO film below the Al2O3 passivation layer changes from a conducting electrode to a semiconducting channel layer simultaneously upon the formation of the passivation layer during thermal annealing. The channel length of the fabricated TFTs is defined by WAl2O3, which can be easily changed with varying EHD jet printing conditions, i.e., no need of replacing the mask for varying patterns. Accordingly, the drain current and resistance of the fabricated TFTs can be modified by varying the WAl2O3. Using the proposed method, a transparent n-type metal-oxide-semiconductor (NMOS) inverter with an enhancement load can be fabricated; the effective resistance of load and drive TFTs is easily tuned by varying the processing conditions using this simple method. The fabricated NMOS inverter exhibits an output voltage gain of 7.13 with a supply voltage of 10 V. Thus, the proposed approach is promising as a low-cost and flexible manufacturing system for multi-item small-lot-sized production of Internet of Things devices.

Vocal Feminization for Transgender Women: Current Strategies and Patient Perspectives.

Voice feminization for transgender women is a highly complicated comprehensive transition process. Voice feminization has been thought to be equal to pitch elevation. Thus, many surgical procedures have only focused on pitch raising for voice feminization. However, voice feminization should not only consider voice pitch but also consider gender differences in physical, neurophysiological, and acoustical characteristics of voice. That is why voice therapy has been the preferred choice for the feminization of the voice. Considering gender difference of phonatory system, the method for voice feminization consists of changing the following four critical elements: fundamental frequency, resonance frequency related to vocal tract volume and length, formant tuning, and phonatory pattern. Voice feminizing process can be generally divided into non-surgical feminization and surgical feminization. As a non-surgical procedure, feminization voice therapy consists of increasing fundamental frequency, improving oral and pharyngeal resonance, and behavioral therapy. Surgical feminization usually can be achieved by external approach or endoscopic approach. Based on three factors (length, tension and mass) of vocal fold for pitch modulation, surgical procedure can be classified as one-factor, two-factors and three-factors modification of vocal folds. Recent systematic reviews and meta-analysis studies have reported positive outcomes for both the voice therapy and voice feminization surgery. The benefits of voice therapy, as it is highly satisfactory, mostly increase vocal pitch, and are noninvasive. However, the surgical voice feminization of three-factors modification of vocal folds is also highly competent and provides a maximum absolute increase in vocal pitch. Voice feminization is a long transition journey for physical, neurophysiological, and psychosomatic changes that convert a male phonatory system to a female phonatory system. Therefore, strategies for voice feminization should be individualized according to the individual's physical condition, the desired change in voice pitch, economic conditions, and social roles.

High Photosensitive Indium-Gallium-Zinc Oxide Thin-Film Phototransistor with a Selenium Capping Layer for Visible-Light Detection.

Visible light can be detected using an indium-gallium-zinc oxide (IGZO)-based phototransistor, with a selenium capping layer (SCL) that functions as a visible light absorption layer. Selenium (Se) exhibits photoconductive properties as its conductivity increases with illumination. We report an IGZO phototransistor with an SCL (SCL/IGZO phototransistor) that demonstrated optimal photoresponse characteristics when the SCL was 150 nm thick. The SCL/IGZO phototransistor exhibited a photoresponsivity of 1.39 × 103 A/W, photosensitivity of 4.39 × 109, detectivity of 3.44 × 1013 Jones, and external quantum efficiency of 3.52 × 103% when illuminated by green light (532 nm). Ultraviolet-visible spectroscopy and ultraviolet photoelectron spectroscopy analysis showed that Se has a narrow energy band gap, in which visible light is absorbed and forms a p-n junction with IGZO so that photogenerated electron-hole pairs are easily separated, which makes recombination more challenging. We show that electrons generated in the SCL flow through the IGZO layer, which enables the phototransistor to detect visible light. Furthermore, the SCL/IGZO phototransistor exhibited excellent durability and reversibility owing to the constant light and dark current and the time-dependent photoresponse characteristics over 8000 s when a red light (635 nm) source was turned on and off at a frequency of 0.1 Hz.

Montelukast Nanocrystals for Transdermal Delivery with Improved Chemical Stability.

A novel nanocrystal system of montelukast (MTK) was designed to improve the transdermal delivery, while ensuring chemical stability of the labile compound. MTK nanocrystal suspension was fabricated using acid-base neutralization and ultra-sonication technique and was characterized as follows: approximately 100 nm in size, globular shape, and amorphous state. The embedding of MTK nanocrystals into xanthan gum-based hydrogel caused little changes in the size, shape, and crystalline state of the nanocrystal. The in vitro drug release profile from the nanocrystal hydrogel was comparable to that of the conventional hydrogel because of the rapid dissolution pattern of the drug nanocrystals. The drug degradation under visible exposure (400-800 nm, 600,000 lux·h) was markedly reduced in case of nanocrystal hydrogel, yielding only 30% and 50% amount of cis-isomer and sulfoxide as the major degradation products, as compared to those of drug alkaline solution. Moreover, there was no marked pharmacokinetic difference between the nanocrystal and the conventional hydrogels, exhibiting equivalent extent and rate of drug absorption after topical administration in rats. Therefore, this novel nanocrystal system can be a potent tool for transdermal delivery of MTK in the treatment of chronic asthma or seasonal allergies, with better patient compliance, especially in children and elderly.

Design and In Vivo Pharmacokinetic Evaluation of Triamcinolone Acetonide Microcrystals-Loaded PLGA Microsphere for Increased Drug Retention in Knees after Intra-Articular Injection.

A novel polymeric microsphere (MS) containing micronized triamcinolone acetonide (TA) in a crystalline state was structured to provide extended drug retention in joints after intra-articular (IA) injection. Microcrystals with a median diameter of 1.7 µm were prepared by ultra-sonication method, and incorporated into poly(lactic-co-glycolic acid)/poly(lactic acid) (PLGA/PLA) MSs using spray-drying technique. Cross-sectional observation and X-ray diffraction analysis showed that drug microcrystals were evenly embedded in the MSs, with a distinctive crystalline nature of TA. In vitro drug release from the novel MSs was markedly decelerated compared to those from the marketed crystalline suspension (Triam inj.®), or even 7.2 µm-sized TA crystals-loaded MSs. The novel system offered prolonged drug retention in rat joints, providing quantifiable TA remains over 28 days. Whereas, over 95% of IA TA was removed from joints within seven days, after injection of the marketed product. Systemic exposure of the steroidal compound was drastically decreased with the MSs, with <50% systemic exposure compared to that with the marketed product. The novel MS was physicochemically stable, with no changes in drug crystallinity and release profile over 12 months. Therefore, the TA microcrystals-loaded MS is expected to be beneficial in patients especially with osteoarthritis, with reduced IA dosing frequency.

Pharmacokinetics and four-week repeated-dose toxicity of hyaluronic acid and ketorolac combination following intra-articular administration in normal rats.

Intra-articular (IA) injection of hyaluronic acid (HA) in combination with nonsteroidal anti-inflammatory drugs, such as ketorolac (KL), have been clinically investigated to provide more rapid and profound pain relief in patients with osteoarthritis. However, its safety, local tolerance, and potential for pharmacokinetic interaction have not been assessed. In this study, the pharmacokinetics and toxicity of a combination of HA and KL were evaluated in normal rats following four-week repeated-dose injection. Rats received HA or KL alone at 4 mg/kg or 16 mg/kg, respectively, or HA/KL combination at 4/4 mg/kg, 4/8 mg/kg, or 4/16 mg/kg on a weekly basis. The rats exhibited temporal, reversible changes in hematology, serum chemistry, and urinalysis caused primarily by KL treatment. No deleterious effects were observed on the joint following repeated IA HA/KL administration, which showed only minimal to mild levels of temporary inflammatory changes in synovial membrane. The plasma KL level following IA injection rose as fast as that of intra-muscular injection, with no alteration with the co-administered HA. In conclusion, repeated IA administration of HA/KL combination was tolerated well in normal rats, encouraging future studies of IA injection of HA/KL combination on osteoarthritis-induced animal models and even patients.

Staged Repair of Truncus Arteriosus Associated with Complete Atrioventricular Septal Defect.

We report a case of successful repair of truncus arteriosus (TA) associated with complete atrioventricular septal defect (c-AVSD) using a staged approach. TA associated with c-AVSD is a very rare congenital cardiac anomaly. No report of successful staged repair in South Korea has yet been published. We performed bilateral pulmonary artery banding when the patient was 33 days old, and total correction using an extracardiac conduit was performed at the age of 18 months. The patient recovered uneventfully and is doing well.

Effect of Zn on Pore Characteristics in Lotus-Type Porous Cu.

The effect of Zn on pore characteristics in lotus-type porous Cu alloy was investigated. The lotustype porous Cu-Zn alloys were fabricated with Zn content from 0.01 to 0.1 at% by the centrifugal casting method. The results demonstrated that the porosity was rarely affected by Zn content. However, the average pore diameter and pore number density of the lotus type porous Cu-Zn alloys were significantly affected by the Zn content. The average pore diameter decreased as the Zn content increased up to 0.01 at%, and then increased as the Zn content increased up to 0.1 at%. In contrast, the variations in the pore number density of the lotus-type porous Cu-Zn alloys showed the reversed tendency with respect to that of the average pore diameter. The increase in heterogeneous nucleation sites for pores attributed to the decreased average pore diameter and the increased pore number density.

Combination therapy of BRAF inhibitors for advanced melanoma with BRAF V600 mutation: a systematic review and meta-analysis.

BACKGROUND: Although BRAF inhibitors have been used to treat advanced melanoma with BRAF mutation, combination strategies are suggested due to acquired resistance to BRAF inhibitors. OBJECTIVE: To assess the efficacy of BRAF inhibitor-based combination therapy for the treatment of advanced melanoma with BRAF mutation. METHODS: We conducted a systematic review and meta-analysis of studies that compared BRAF inhibitor-based combination therapy with BRAF inhibitor monotherapy. We searched MEDLINE, EMBASE, the Cochrane Library and relevant conference proceedings. The random-effects inverse variance and Mantel-Haenszel methods were used to pool the results. RESULTS: Four randomized controlled trials and one cohort study were identified. A combination therapy with BRAF inhibitors and MEK inhibitors was used in all studies. The combined hazard ratios of overall survival (OS) and progression-free survival (PFS) comparing combination therapy with monotherapy were 0.70 [95% confidence interval (CI) 0.62-0.78] and 0.59 (95% CI 0.55-0.63), respectively. The combined risk ratio of objective response rate (ORR) was 1.30 (95% CI 1.20-1.40), which meant more patients achieved complete/partial responses in combination therapy group than those in the monotherapy group. CONCLUSIONS: Combination therapy with BRAF inhibitors and MEK inhibitors significantly improved OS, PFS, and ORR in patients with advanced melanoma with BRAF mutation.

State of education regarding ultrasound-guided interventions during pain fellowships in Korea: a survey of recent fellows.

BACKGROUND: Recently, the use of ultrasound (US) techniques in regional anesthesia and pain medicine has increased significantly. However, the current extent of training in the use of US-guided pain management procedures in Korea remains unknown. The purpose of the present study was to assess the current state of US training provided during Korean Pain Society (KPS) pain fellowship programs through the comparative analysis between training hospitals. METHODS: We conducted an anonymous survey of 51 pain physicians who had completed KPS fellowships in 2017. Items pertained to current US practices and education, as well as the types of techniques and amount of experience with US-guided pain management procedures. Responses were compared based on the tier of the training hospital. RESULTS: Among the 51 respondents, 14 received training at first- and second-tier hospitals (Group A), while 37 received training at third-tier hospitals (Group B). The mean total duration of pain training during the 1-year fellowship was 7.4 months in Group A and 8.4 months in Group B. Our analysis revealed that 36% and 40% of respondents in Groups A and B received dedicated US training, respectively. Most respondents underwent US training in patient-care settings under the supervision of attending physicians. Cervical root, stellate ganglion, piriformis, and lumbar plexus blocks were more commonly performed by Group B than by Group A (P < 0.05). CONCLUSIONS: Instruction regarding US-guided pain management interventions varied among fellowship training hospitals, highlighting the need for the development of educational standards that mandate a minimum number of US-guided nerve blocks or injections during fellowships in interventional pain management.