Effect Of Branch Length Research Articles

Effect of Branch Length on the Structural and Separation Properties of Hyperbranched Poly(1,3-dioxolane)

Polymers containing poly(ethylene oxide) (PEO) demonstrate superior membrane CO2/N2 separation properties owing to their polar ether oxygen groups exhibiting strong affinity toward CO2. Poly(1,3-dioxolane) (PDXL) shows an ether oxygen content higher than PEO and is expected to have higher CO2/N2 solubility selectivity. However, similar to PEO, the high crystallinity of PDXL greatly reduces its gas permeability. Herein, amorphous PDXL-based hyperbranched polymers were synthesized by ring opening of 1,3-dioxolane (DXL) to form poly(1,3-dioxolane) acrylate (DXLAn) followed by photopolymerization. The repeating unit of DXL (n) or branch length was systematically varied from 4 to 12 to yield amorphous polymers. The chemical and physical properties of the obtained polymers (PDXLAn) were thoroughly evaluated and used to interpret pure- and mixed-gas transport characteristics. The polymers exhibit attractive CO2/N2 and CO2/CH4 separation properties. For example, PDXLA8 exhibits a CO2 permeability of 220 Barrer and CO2/N2 selectivity of 56 at 35 °C, surpassing Robeson’s 2008 upper bound, and it shows robust separation performance when evaluated with simulated flue gas at 60 °C. This study demonstrates that hyperbranched structures are an effective route to construct amorphous yet highly polar polymers and that chain end groups are instrumental in determining the structural and gas transport characteristics.

Effect of branch length and tortuosity on the outcomes of branched endovascular repair of thoracoabdominal aneurysms using self-expandable bridging stent graft

ObjectiveWe investigated the effect of the length and tortuosity of directional branches on the mid-term outcomes of branched endovascular aneurysm repair (BEVAR) for thoracoabdominal aortic aneurysms (TAAA). MethodsWe retrospectively reviewed single-center data of consecutive patients who had undergone BEVAR for TAAA from 2015 to 2019. Three-dimensional computed tomography angiogram reconstructions (Aquarius iNtuition software; TeraRecon, Durham, NC) of the first postoperative imaging studies were used to measure the branch total length (TL), branch vertical length (VL), and branch tortuosity index (TI). The branch TL was measured as the centerline distance between the branch proximal radiopaque marker and the distal edge of the bridging stent. The VL was measured as the centerline distance between the branch distal radiopaque marker and the origin of the target artery. The TI was measured in accordance with the Society for Vascular Surgery reporting standard. The primary end point was freedom from branch instability, defined as any branch-related death, occlusion, or rupture and any reintervention for stenosis, endoleak, or disconnection. Cox proportional hazards were used to identify predictors of branch instability. A penalized spline function was used to identify the relationship between branch instability and the branch TL and VL. ResultsPostimplantation analysis was conducted on 32 TAAAs (extent I-III, n = 18 [56%]; extent IV, n = 14 [44%]), with 123 arteries included through a directional branch. A covered self-expanding bridging stent was used in all cases. Intraoperative reinforcement with an additional bare metal stent was performed in 85 cases (69%). The overall freedom from branch instability at 3 years was 88% (95% confidence interval [CI], 81%-94%). Five cases of occlusion and eight cases of branch-related endoleak occurred. A concomitant endoleak and severe stenosis requiring intervention developed in three cases. The Cox model with splines showed that the minimal risk of branch instability was achieved with a branch TL of 60 to 100 mm (P = .002) and a branch VL of 25 to 50 mm (P = .038). A TI of >1.15 was a predictor of branch complications (hazard ratio [HR], 8.6; 95% CI, 2.4-31.4; P < .001). After multivariate analysis, aneurysm diameter (HR, 1.08; 95% CI, 0.03-1.15; P = .003), TI >1.15 (HR, 6.81; 95% CI, 2.17-27.33; P < .001), and TL <60 or >100 mm (P = .002) were significantly associated with branch instability. ConclusionsThe branch length and TI seemed to play an important role in BEVAR outcomes. The lowest branch instability rates were obtained with a branch TL of 60 to 100 mm, and this should be considered during planning and implantation. A branch TI >1.15 might require a more strict monitoring to prevent mid- and long-term complications.

Effect of Branch Length and Tortuosity on the Outcomes of Branched Endovascular Repair of Thoracoabdominal Aneurysms

The objective was to investigate the effect of length and tortuosity of directional branches on the midterm outcomes of branched endovascular aneurysm repair (BEVAR) for thoracoabdominal aortic aneurysms (TAAAs).

Effects of branch length and chamfer on flow-induced acoustic resonance in closed side branches

The flow-induced acoustic resonance phenomenon may produce excessive vibrations of components in pipe systems. In this study, the effects of branch length and edge geometry on the acoustic resonance characteristics of closed side branches are investigated experimentally. Three different aspect ratios of L/d = 8, 10 and 12, where L is the branch length and d is the branch diameter, are investigated with Mach number up to 0.28. The results show that, for all the tested configurations, the second hydrodynamic mode only excites the first acoustic mode due to the small diameter of the side branches. The maximum normalized pulsation amplitude at the first acoustic mode decreases in branch length. The influence of branch length on the Strouhal numbers at onset of resonance is weak. It is about 0.55 for the first hydrodynamic mode in the case of sharp edge. The maximum normalized pulsation amplitudes are excited at a Strouhal number close to 0.4. Two different chamfers of angle 45° and C = 2.5 and 5 mm, where C is the width of the chamfered edge, are investigated. The results illustrate that the maximum normalized pulsation amplitude and the Strouhal number at onset of resonance both decrease significantly in chamfer width, which indicates chamfering is an effective method to attenuate undesirable acoustic resonance induced by closed side branches in pipe system.

Improve the Plasmonic Spectral Detection of Alpha-Fetoprotein: the Effect of Branch Length on the Coagulation of Gold Nanostars

A sensitive spectral sensing method for detection of alpha-fetoprotein (AFP) was proposed based on the intense aggregation of colloidal gold nanostars. It has been found that the intensity of the infrared plasmonic absorption peak of the gold nanostar colloid is very sensitive to the addition of AFP. Because of the electrostatic attraction-induced particle aggregation and coagulation, the plasmonic absorbance corresponding to the suspending nanostars fades down rapidly as the AFP concentration is increased. This spectral sensitivity based on the particle aggregation could be effectively improved by increasing the branch length of the gold nanostars, and the limit of detection reaches 2 pg/mL. The corresponding physical mechanism has been illuminated by the tip effect-enhanced surface charge concentration and electrostatic attraction.

Effect of Branch Length on 13C NMR Relaxation Properties in Molten Poly[ethylene‐co‐(α‐olefin)] Model Systems

AbstractThe potential of branch length discrimination for branches containing six and more carbons via bulk NMR relaxation properties in the melt‐state has been explored. A systematic increase in the 13C spin‐lattice relaxation time (T) of the terminal branch carbons 1 and 2 was observed when the branch increased from 6 to 16 carbons in length. The measurement of T via inversion recovery at high‐field showed the most reliable data. The effects of saturation and NOE were addressed by using recycle delays longer than 5 × T and the use of the saturation recovery was found to be unsatisfactory. All nuclear relaxation times were determined in a highly time efficient manner using a previously developed melt‐state MAS NMR method.magnified image

Saccharide-branched Cyclodextrins as Targeting Drug Carriers

A synthetic series of heptakis-galactose-branched cyclodextrins (termed CDs) having a longer spacer arm using two amino-caproic acids as an enlarging unit were prepared. Starting with heptakis-amino-β-CD or heptakis-amino-caproic-amide-β-CD, treated with galactosyl-glucono-amide-caproic acid, the new compounds heptakis (Gal-cap1)-CD (4) or heptakis (Gal-cap2)-CD (5) were obtained. The longer galactose spacer arm extremely favors the PNA association. The effect of branch length on K with PNA was enhanced up to 138-fold 3 as well as with DXR enhanced up to 81-fold. Hexakis (Gal-cap2)-CD (6) was prepared and the association constants with rat liver cells were observed to be 2.5 × 1010 M−1. A multi-high mannose type oligosaccharide branched CD (7) showed a large association constant with DXR up to 1.1 × 109 M−1. The two-dimensional map for the association constants of newly synthesized oligosaccharide-branched CDs toward lectin or liver cells versus the association constants toward a drug (doxorubicin) suggested a method of finding a better targeting drug carrier. The structural effect of the oligosaccharide-CDs showed that the number and length of the branch were dominant factors in designing for enhanced dual recognition.

Water availability and branch length determine delta(13)C in foliage of Pinus pinaster.

The stable carbon isotope composition (delta(13)C) of foliage integrates signals resulting from environmental and hydraulic constraints on water movement and photosynthesis. We used branch length as a simple predictor of hydraulic constraints to water fluxes and determined the response of delta(13)C to varying water availability. Foliage up to 6 years old was taken from Pinus pinaster Ait. trees growing at four sites differing in precipitation (P; 414-984 mm year(-1)) and potential evaporation (ET; 1091-1750 mm year(-1)). Branch length was the principal determinant of temporal trends in delta(13)C. The strong relationship between delta(13)C and branch length was a function of hydraulic conductance, which was negatively correlated with branch length (r(2) = 0.84). Variation in P and ET among sites was reflected in delta(13)C, which was negatively correlated with P/ET (r(2) = 0.66). However, this analysis was confounded by differences in branch length. If the effects of branch length on delta(13)C were first removed, then the 'residual' delta(13)C was more closely related to P/ET (r(2) = 0.99), highlighting the importance of accounting for variation in hydraulic constraints to water flux between sites and years. For plant species that exhibit considerable phenotypic plasticity in response to changes in environment (e.g., variation in leaf area, branch length and number, or stem form), the environmental effects on delta(13)C in foliage can only be reliably assessed if deconvoluted from hydraulic constraints.

Effects of branch length on carbon isotope discrimination in Pinus radiata.

Gas exchange was measured on a pruned Pinus radiata D. Don hedge and on a long-branch P. radiata tree near Hamilton, New Zealand, in spring 1993 when soil water content was close to field capacity. Foliage at the end of long branches (9.0 m) showed a marked drop in net photosynthetic rate and stomatal conductance as the saturation deficit increased, whereas foliage on short branches (0.5 m) showed little change. Mean foliage delta(13)C was -30.1 per thousand for short branches and -26.3 per thousand for long branches. Foliage delta(13)C was correlated with branch length in two genetically improved P. radiata seedlots at four stocking densities. The multinodal seedlot had shorter branches and more (13)C-depleted foliage compared with branches and foliage from the long internode seedlot. There was a strong effect of stocking density on carbon isotope composition in both seedlots. We conclude that branch morphology affects foliage gas exchange properties and foliage carbon isotope composition.