Single Looping Research Articles

Two-way adjustable double-knots intrascleral fixation and single sclerotomy looping technique: a novel minimal invasive adjustable intraocular lens fixation technique

BackgroundIOL fixation without capsular support presents challenges for surgeons. Although innovative techniques were developed to address subluxated IOLs, adjustable IOL fixation methods are seldom reported. We introduce a novel two-way adjustable double-knots intrascleral fixation combined with single sclerotomy looping technique for fixing intraocular lenses (IOL) or IOL-capsular bags.MethodsA bent 30-gauge needle threaded with 8 − 0 polypropylene was introduced into the eye. A gripping forceps assisted the haptic looping. Two overhand knots were made with 8 − 0 polypropylene thread. The knots were incarcerated into a scleral tunnel made by a 30-gauge needle, with two ends of the thread left at each side of the tunnel. The IOL was adjusted to the premium position with adequate tension by pulling either end of the threads. The study included 19 eyes with aphakia, subluxated IOL-capsular bags, or subluxated crystalline lenses. The mean followed up period was 18.9 ± 7.1 months with evaluations of uncorrected visual acuity (UCVA), intraocular pressure, slit-lamp examination, and swept-source optical coherence tomography of the anterior segment.ResultsUCVA increased from 1.28 ± 0.74 at baseline to 0.44 ± 0.51 (logMAR) at final visit (P < 0.001). All IOLs were fixed well-centered. The mean IOL tilt was 3.5°±1.1°. Postoperative complications included transient IOP elevation (15.8%), hypotony (10.5%), and cystoid edema (5.3%) which resolved within 4 weeks.ConclusionsWe presented a novel adjustable technique for IOL fixation, which stabilize IOLs by using an intrascleral double-knots structure. This technique minimized surgical manipulations by using a single sclerotomy looping technique without large conjunctival dissection and scleral flap creation. The technique offers a reliable and optimal IOL positioning and improved visual outcomes in patients undergoing scleral fixed IOL implantation.

A novel calcium looping–integrated NGCC power plant configuration for carbon capture and utilization—Comprehensive performance analysis

Energy plays a pivotal role in industrial development of any country. At present, most of the countries are utilizing fossil fuels, mainly coal and natural gas as energy sources for power production. However, these sources emit high amounts of carbon dioxide (CO2) into the atmosphere resulting in global warming. Hence, the fossil fuel–based thermal power plants need to be integrated with CO2 sequestration and utilization processes for sustainable power production. In this work, four natural gas combined cycle (NGCC) power plant configurations are proposed—two with CO2 capture and sequestration (single and double calcium looping units) and two with CO2 capture and utilization (for production of dimethyl ether). Energy, exergy, environmental, and economic analyses are carried out to assess the performance of the proposed novel configurations against the conventional NGCC power plant. These analyses reveal that the NGCC power plant integrated with double calcium looping unit captures 91.32% of CO2 with an energy penalty of 6.73%. The proposed CO2 capture and utilization integrated configurations have low electrical power output; however, the conversion of CO2 to high energy density dimethyl ether (DME) product resulted in overall energy and exergy efficiency gain. The CO2 capture and utilization configuration integrated with solar energy is able to convert the total captured CO2 to DME and makes the process sustainable.

Simplified abductor pollicis longus suspension interposition arthroplasty for thumb carpometacarpal joint osteoarthritis

PurposeThe primary treatment goals for advanced-stage thumb carpometacarpal (CMC) joint osteoarthritis are complete pain relief and restoration of thumb strength. The purpose of the present study was to introduce a variation of the abductor pollicis longus (APL) suspension arthroplasty using a single looping of a radial slip from the APL tendon around the flexor carpi radialis (FCR) tendon combined with RegJoint™ interposition and to determine its efficacy in the treatment of thumb CMC joint osteoarthritis.MethodsBetween 2015 and 2017, 21 patients were included. The average age was 60.8 years (range 48–79). The mean follow-up was 27.7 months (range 8–50). Evaluation included pain, radial and palmar abduction, tip pinch and grip strength, and Disabilities of the Arm, Shoulder, and Hand (DASH) score.ResultsPain averaged 0.3 (range 0–4) at rest and 1.4 (range 0–4) on exertion. The radial and palmar abduction were 97% and 99% compared to the contralateral side. The tip pinch and grip strength were 4.1 kg (range 3–6.5) and 22 kg (range 13.3–40), respectively. The DASH score accounted for 18.5 (range 0.8–41.7).ConclusionThe modified APL suspension interposition arthroplasty was an efficient and simplified option for the treatment of thumb CMC joint osteoarthritis, with results comparable or better than other published procedures. The APL suspension technique was easy to perform avoiding difficult bone tunneling and incision of the FCR tendon. The RegJoint™ interposition as spacer prevented impingement of the first metacarpal base on the second metacarpal base or the trapezoid bone.

Coal Refining Chemical Looping Systems with CO2 as a Co-Feedstock for Chemical Syntheses

This study quantifies the advantages of a chemical looping reducer reactor modularization strategy that leverages two or more reducer reactors operating in parallel to enhance syngas production beyond what is achievable by a single reducer reactor or conventional processes. The modularized system incorporates CO2 capture and utilization as a feedstock in an iron–titanium composite metal oxide based chemical looping system to enhance coal based chemical production. Simulations conducted in ASPEN Plus software suggest that adopting a cocurrent moving bed reducer reactor based modularization strategy can improve syngas yield by greater than 11% over a single chemical looping reducer reactor. Experiments conducted on a bench scale reducer reactor confirm the findings of the simulations. The modularization simulation was scaled up and incorporated into commercial sized methanol and acetic acid production plants. Chemical looping modularization demonstrates the ability to reduce coal consumption by 25% over a b...

Fast Monte Carlo simulation for particle coagulation in population balance

The Monte Carlo (MC) method for population balance modeling (PBM) has become increasingly popular because the discrete and stochastic nature of the MC method is especially suited for particle dynamics. However, for the two-particle events (typically, particle coagulation), the double looping over all simulation particles is required in normal MC methods, and the computational cost is O(Ns2), where Ns is the simulation particle number. This paper proposes a fast random simulation scheme based on the differentially-weighted Monte Carlo (DWMC) method. The majorant of coagulation kernel was introduced to estimate the maximum coagulation rate by a single looping over all particles rather than the double looping. The acceptance–rejection process then proceeded to select successful coagulation particle pairs randomly, and meanwhile the waiting time (time-step) for a coagulation event was estimated by summing the coagulation kernels of rejected and accepted particle pairs. In such a way, the double looping is avoided and computational efficiency is greatly improved as expected. Five coagulation cases for which analytical solutions or benchmark solutions exist were simulated by the fast and normal DWMC, respectively. It is found the CPU time required is orders of magnitude lower and only increases linearly with Ns; at the same time the computational accuracy is guaranteed very favorably.

Manual Wheelchair Propulsion Patterns on Natural Surfaces During Start-Up Propulsion

Koontz AM, Roche BM, Collinger JL, Cooper RA, Boninger ML. Manual wheelchair propulsion patterns on natural surfaces during start-up propulsion. Objectives To classify propulsion patterns over surfaces encountered in the natural environment during start-up and compare selected biomechanical variables between pattern types. Design Case series. Setting National Veterans Wheelchair Games, Minneapolis, MN, 2005. Participants Manual wheelchair users (N=29). Intervention Subjects pushed their wheelchairs from a resting position over high-pile carpet, over linoleum, and up a ramp with a 5° incline while propulsion kinematics and kinetics were recorded with a motion capture system and an instrumented wheel. Main Outcome Measures Three raters classified the first 3 strokes as 1 of 4 types on each surface: arc, semicircular (SC), single looping over propulsion (SL), and double looping over propulsion (DL). The Fisher exact test was used to assess pattern changes between strokes and surface type. A multiple analysis of variance test was used to compare peak and average resultant force and moment about the hub, average wheel velocity, stroke frequency, contact angle, and distance traveled between stroke patterns. Results SL was the most common pattern used during start-up propulsion (44.9%), followed by arc (35.9%), DL (14.1%), and SC (5.1%). Subjects who dropped their hands below the rim during recovery achieved faster velocities and covered greater distances (.016≤ P≤.075) during start-up on linoleum and carpet and applied more force during start-up on the ramp compared with those who used an arc pattern ( P=.066). Conclusions Classifying propulsion patterns is a difficult task that should use multiple raters. In addition, propulsion patterns change during start-up, with an arc pattern most prevalent initially. The biomechanical findings in this study agree with current clinical guidelines that recommend training users to drop the hand below the pushrim during recovery.

Stroke Pattern and Handrim Biomechanics for Level and Uphill Wheelchair Propulsion at Self-Selected Speeds

Richter WM, Rodriguez R, Woods KR, Axelson PW. Stroke pattern and handrim biomechanics for level and uphill wheelchair propulsion at self-selected speeds. Objectives To investigate the natural stroke patterns of wheelchair users pushing on a level surface, to determine if users adapt their stroke patterns for pushing uphill, and to assess whether there are biomechanic advantages to one or more of the stroke patterns. Design Case series. Setting Biomechanics laboratory. Participants Twenty-six manual wheelchair users with a spinal cord injury. Intervention Subjects pushed their own wheelchairs at self-selected speeds on a research treadmill set to level, 3°, and 6° grades. Stroke patterns were measured using a motion capture system. Handrim biomechanics were measured using an instrumented wheel. Main Outcome Measures Stroke patterns were classified for both level and uphill propulsion according to 1 of 4 common classifications: arcing, semi-circular, single-looping (SLOP), and double-looping (DLOP). Biomechanic outcomes of speed, peak handrim force, cadence, and push angle were all compared across stroke classifications using an analysis of variance. Results Only 3 of the 4 stroke patterns were observed. None of the subjects used the semi-circular pattern. For level propulsion, the stroke patterns were fairly balanced between arcing (42%), SLOP (31%), and DLOP (27%). Subjects tended to change their stroke pattern for pushing uphill, with 73% of the subjects choosing the arcing pattern by the 6° grade. No statistically significant differences were found in handrim biomechanics or subject characteristics across stroke pattern groups. Conclusions Wheelchair users likely adapt their stroke pattern to accommodate their propulsion environment. Based on the large percentage of subjects who adopted the arcing pattern for pushing uphill, there may be benefits to the arcing pattern for pushing uphill. In light of this and other recent work, it is recommended that clinicians not instruct users to utilize a single stroke pattern in their everyday propulsion environments.

Dynamics of Single DNA Looping and Cleavage by Sau3AI and Effect of Tension Applied to the DNA

Looping and cleavage of single DNA molecules by the two-site restriction endonuclease Sau3AI were measured with optical tweezers. A DNA template containing many recognition sites was used, permitting loop sizes from ∼10 to 10,000 basepairs. At high enzyme concentration, cleavage events were detected within 5 s and nearly all molecules were cleaved within 5 min. Activity decreased ∼10-fold as the DNA tension was increased from 0.03 to 0.7 pN. Substituting Ca 2+ for Mg 2+ blocked cleavage, permitting measurement of stable loops. At low tension, the initial rates of cleavage and looping were similar (∼0.025 s −1 at 0.1 pN), suggesting that looping is rate limiting. Short loops formed more rapidly than long loops. The optimum size decreased from ∼250 to 45 basepairs and the average number of loops (in 1 min) from 4.2 to 0.75 as tension was increased from 0.03 to 0.7 pN. No looping was detected at 5 pN. These findings are in qualitative agreement with recent theoretical predictions considering only DNA mechanics, but we observed weaker suppression with tension and smaller loop sizes. Our results suggest that the span and elasticity of the protein complex, nesting of loops, and protein-induced DNA bending and wrapping play an important role.

Direct, Androgen Receptor-Mediated Regulation of the FKBP5 Gene via a Distal Enhancer Element

Androgen signaling via the androgen receptor (AR) transcription factor is crucial to normal prostate homeostasis and prostate tumorigenesis. Current models of AR function are predominantly based on studies of prostate-specific antigen regulation in androgen-responsive cell lines. To expand on these in vitro paradigms, we used the mouse prostate to elucidate the mechanisms through which AR regulates another direct target, FKBP5, in vivo. FKBP5 encodes an immunophilin that has been previously implicated in glucocorticoid and progestin signaling pathways and that likely influences prostate physiology in the presence of androgens. In this work, we show that androgens directly regulate FKBP5 via an interaction between the AR and a distal enhancer located 65 kb downstream of the transcription start site in the fifth intron of the FKBP5 gene. We have found that AR selectively recruits cAMP response element-binding protein to this enhancer. These interactions, in turn, result in chromatin remodeling that affects the enhancer proper but not the FKBP5 locus as a whole. Furthermore, in contrast to prostate-specific antigen-regulatory mechanisms, we show that transactivation of the FKBP5 gene does not rely on a single looping complex to mediate communication between the distal enhancer and proximal promoter. Rather, the distal enhancer complex and basal transcription apparatus communicate indirectly with one another, implicating a regulatory mechanism that has not been previously appreciated for AR target genes.

Common role for each of the cGATA-4/5/6 genes in the regulation of cardiac morphogenesis.

The GATA-4/5/6 genes encode transcription factors implicated previously in the regulation of cardiac-specific differentiation programs. However, recent analyses of mouse GATA-4 null mutations found evidence for function in endoderm development (in vitro) and embryonic morphogenesis (in vivo). Whether each of the three cardiac-associated GATA factors function within distinct or common developmental programs was previously untested; past studies defined specific and distinct roles for each of the GATA-1/2/3 genes in embryonic hematopoiesis. In this study, we compare the transcript patterns of cGATA-4/5/6 during chick embryogenesis. Each of the three GATA factors is expressed in a similar pattern within gastrulating cells of the primitive streak, prior to determination of the cardiomyocyte progenitors, and later within the lateral plate mesoderm and associated endoderm layer. The patterns overlap but extend beyond the presumptive cardiomyocyte population expressing cNkx-2.5. Later in development, cGATA-4/5/6 are all transcribed throughout the differentiating heart, in similar but not identical patterns, within the endocardium, myocardium, and great vessels. In order to test the function of GATA factors during chick cardiogenesis, embryos were cultured in vitro in the presence of antisense oligomers designed to deplete specifically transcripts encoding cGATA-4/5/6, beginning around stage 7. When oligomers are used to target transcripts for all three genes, a high percentage of the embryos develop abnormal hearts related to the failure to form a normal primitive heart tube. In the most severe phenotype, cardiac bifida results in two bilateral beating hearts. In some embryos, the paired heart primordia undergo partial fusion but fail to form a single looping heart tube. In all cases, cellular differentiation is not obviously affected, as the abnormal hearts form beating tissue. Depletion of transcripts encoding any single GATA factor, or any combination of two GATA factors, does not affect development. The partial depletion of all three genes in chick results in a remarkably similar phenotype compared to the null GATA-4 mutation in mouse. Therefore, in the chick, each of the GATA-4/5/6 genes functions in a common pathway, at the time of cardiac crescent formation, for regulating early embryonic cardiac morphogenesis, apparently associated with embryonic folding or the migration of primordia to form a primitive tube.

Some new aspects concerning particle hardening mechanisms in γ' precipitating nickel-base alloys—II. Experiments

Experiments are presented examining the theoretical concept described in the preceding paper (part I). The RT yield stress of the γ'(Ni 3Al) strengthened Nickel base alloys Nimonic PE 16 and Nimonic 105 has been measured in compression, the γ'-particle diameter (3–720 nm) and the precipitated volume fraction (4–51%) being varied over a wide range. The analysis of the experimental data starts from the assumption that solid solution hardening of matrix and γ'-particle hardening do not superimpose by linear addition, but according to the ‘ 3 2 -law’. The measured relationships can be described but qualitatively by conventional hardening models which actually hold for small volume fractions. In particular, the transition from cutting of γ'-particles by paired dislocations to single dislocation Orowan looping occurs at large (overaged) spherical particles as expected by theory. However, in the range of small particles considerable discrepancies arise. Here, the new theory of Labusch and Schwarz has to be applied, fitting experimental data thoroughly to the respective model. The interpretation of the mechanical relationships is supported by TEM observation of the dislocation structure.