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•Starch nanoparticles (SNP) were grafted with synthetic polymers using NMP and the grafting from approach.•A three-step procedure was followed to prepare the bio-synthetic hybrid ...materials.•The grafting from reactions were confirmed by 1H NMR, FTIR, TGA and elemental analysis.•Varying amounts of poly(methyl methacrylate-co-styrene), poly(methyl acrylate) and poly(acrylic acid) were grafted from SNP.•High monomer conversions (>90%) were obtained in a relatively short reaction time (<2 h).
Starch nanoparticles (SNP) are attracting increased attention as a renewable bio-based alternative to petroleum-based polymers in the materials community. In this work, we describe the grafting from of SNP with synthetic polymers via nitroxide-mediated polymerization (NMP). Varying amounts of poly(methyl methacrylate-co-styrene) (P(MMA-co-S)), poly(methyl acrylate) (PMA) and poly(acrylic acid) (PAA) were grafted from the surface of SNP in a three-step process. The grafting of synthetic polymers from the surface of SNP was confirmed by FTIR, 1H NMR, elemental analysis and thermogravimetric analysis. These new tailor-made starch-based hybrid materials could find use in paper coatings, adhesives, paints, as well as in polymer latex applications.
This study examined travel patterns of pupils from four secondary schools in Austria and Germany. Their mobility behavior was examined using a one-week travel diary in a typical school week. This ...paper examines objective determinants (in particular settlement pattern and trip characteristics) of mode choice. We used a Bayesian approach for nonlinear Structural Equation Modeling (SEM) of binary response variables to assess the effects of external factors on the choice of travel modes. The focus lies on the competitiveness between car and transit. The results indicate that children's modal choices are influenced by trip length and the service quality of motorized modes. A key finding is that school trips and non-school trips are very different. School trips are quite affine to transit even in rural areas, given a sufficient service quality, which can easily be provided by a school bus system. Long school trips increase the frequency of transit use. Non-school trips, however, are much more affine to car ridership, if trip length exceeds the range for walking and cycling.
Starch nanoparticles (SNP) were modified with synthetic polymers using the “grafting to” approach and nitroxide-mediated polymerization. SG1-capped poly(methyl methacrylate-co-styrene) ...(P(MMA-co-S)) copolymers with low dispersity and high degree of livingness were first synthesized in bulk. These macroalkoxyamines were then grafted to vinyl benzyl-functionalized SNP to obtain biosynthetic hybrids. The grafted materials, SNP-g-P(MMA-co-S), were characterized by 1H NMR, FTIR, TGA, and elemental analysis. The total amount of grafted polymer and the grafting efficiency were evaluated for different molecular weights (5870–12150 g·mol–1) of the grafted polymer, the polymer addition approach (batch or semibatch) and the initial polymer loading (2.5, 5, or 10 g polymer/g SNP). The proposed approach presented in this work to graft modify SNP allows for a precise surface modification of the nanoparticles, while permitting that the final properties of the resulting biohybrid to be tunable according to the choice of polymer grafted.
Nitroxide‐mediated polymerization (NMP) is employed to graft synthetic polymers from polysaccharides. This work demonstrates the first successful polymer grafting from starch nanoparticles (SNPs) via ...NMP. To graft synthetic polymers from the SNPs' surface, the SNPs are first functionalized with 4‐vinylbenzyl chloride prior to reaction with BlocBuilder MA yielding a macroinitiator. Methyl methacrylate with styrene, acrylic acid, or methyl acrylate are then grafted from the SNPs. The polymerizations exhibited linear reaction kinetics, indicating that they are well controlled. Thermal gravimetric analysis and spectroscopic techniques confirmed the synthesis of the precursors materials and the success of the grafting from polymerizations. The incorporation of hydrophobic synthetic polymers on hydrophilic SNPs yields new hybrid materials that could find use in several industrial applications including paper coatings, adhesives, and paints.
Hybrid materials comprising starch nanoparticles (SNPs) and synthetic polymers are prepared via nitroxide‐mediated polymerization (NMP). Initially, the SNPs are functionalized with 4‐vinylbenzyl chloride (VBC), followed by the reaction with an alkoxyamine (Blocbuilder) to form a macroinitiator. Finally, synthetic polymers are grafted from the surface of the SNPs via NMP.
Statins have been reported to reduce the rates of recurrence and improve the resolution of chronic subdural hematomas (cSDHs) treated surgically or conservatively. No studies have investigated the ...effect of statins in patients treated with middle meningeal artery embolization.
We performed a retrospective search of our cSDH database to identify patients treated with middle meningeal artery embolization alone. Only patients with at least 1 noncontrast computed tomography scan obtained 3–12 weeks after embolization were included. Hematoma volumes were measured at baseline and last noncontrast computed tomography available. The volumes, volume reduction, speed of resolution, and recurrence were compared between patients already receiving statin therapy when admitted and those who were not.
Forty-six patients with 50 cSDHs were included (statins, 17 patients with 18 cSDHs vs. nonstatins, 29 patients with 32 cSDHs). The statin group had a significantly higher rate of hyperlipidemia (statin, 64.7% vs. nonstatin, 31%, P = 0.03) but similar demographics, remaining comorbidities, medications, and hematoma thickness, axial and coronal lengths, and baseline volumes. The time between procedure and last noncontrast computed tomography scan was similar between groups. There were no differences between the groups regarding volume reduction, final volume, speed of resolution, complete resolution, and recurrence.
Patients treated with middle meningeal artery embolization alone who were on statin therapy had no differences in cSDH resolution or recurrence compared to those who were not on statin therapy. It is possible that the anti-inflammatory effects of statins may not be relevant when supply to the dura is interrupted by treatment with embolization.
Lumbar spine fusion surgery is traditionally performed with rigid fixation. Because the rigidity is often supraphysiologic, semirigid rods were developed. To the best of our knowledge, a ...comprehensive evaluation of rod material type on surgical outcomes has yet to be conducted.
A systematic review based on PRISMA guidelines was conducted across 3 electronic databases. After examination for inclusion and exclusion criteria, data were extracted from the studies.
Seventeen studies, including 1399 patients, were included in this review. The mean rigid rod fusion rate is 92.2% and 95.5% for semirigid rods (P = 0.129). The mean improvement in back pain was 60.6% in rigid rods and 71.6% in semirigid rods. The improvement in leg pain was 81.9% and 77.2%, respectively. There were no differences in visual analog scale back pain score (P = 0.098), visual analog scale leg pain score (P = 0.136), or in functional improvement between rigid and semirigid rods (P = 0.143). There was no difference (P = 0.209) in the reoperation rate between rigid rods (13.1%) and semirigid rods (6.5%). There was a comparable incidence of adjacent segment disease (3%), screw fracture (1.7%), and wound infection (1.9%) between rod material types.
There is a moderate level of evidence supporting that surgical intervention results in high fusion rates regardless of rod material type. Surgical intervention improves back pain, leg pain, and function, with neither material type showing clear superiority. There are comparable rates of reoperation, development of adjacent segment disease, development of mechanical complications, and incidence of infection in both rigid and semirigid rods. Further studies regarding rod material type are warranted.
We present a case of acute onset of blindness treated with venous sinus stenting in the hyperacute period (24–48 h). The patient had not been diagnosed previously with idiopathic intracranial ...hypertension and presented at an outside facility with a short history of headache, nausea, vomiting and visual deficits. Initial management included lumbar punctures for pressure relief. Unfortunately, the patient's condition deteriorated and she experienced the rapid onset of blindness. Within 24–48 h of blindness onset, she was transferred to our institution for emergent endovascular stenting of the venous sinuses. The intervention resulted in improvement of symptoms and recovery of visual acuity over a short-term follow-up period.
Cold water-soluble starch (CWS) is a polysaccharide that is industrially important for several applications including paper coatings, but the high viscosity of starch solutions limits the amount of ...starch that can be incorporated in many applications. Due to the poor mechanical properties of starch and poor dispersibility of starch in hydrophobic matrices, it is often chemically modified to make it more useful. Herein, we report the first grafting from (co)polymerisation of CWS via nitroxide-mediated polymerisation (NMP) of methyl methacrylate- co -styrene, methyl acrylate, and acrylic acid. Our three step approach consists of: (1) modification of CWS with 4-vinylbenzyl chloride; (2) functionalisation with 2-methyl-2- N -tertbutyl- N -(diethoxy-phosphoryl-2,2-dimethylpropyl)-aminoxy propionic acid initiator; and (3) grafting from (co)polymerisation via NMP. The (co)polymerisations were well controlled showing linear reaction kinetics for all monomers and relatively low dispersities (<1.5) for the methyl methacrylate- co -styrene grafts. Decreasing the initial monomer concentrations for all monomers increased the linearity of the reaction kinetics demonstrating greater control. By varying the polymerisation time or initial monomer concentration, the graft polymer content could be tuned as desired.
Lateral mass screw (LMS) fixation for the treatment of subaxial cervical spine instability or deformity has been traditionally associated with few neurovascular complications. However, cervical ...pedicle screw (CPS) fixation has recently increased in popularity, especially with navigation assistance, because of the higher pullout strength of the pedicle screws. To their knowledge, the authors conducted the first meta-analysis comparing the complication rates during and/or after CPS and LMS placement for different pathologies causing cervical spine instability. A systematic literature search of PubMed and Embase from inception to January 12, 2021 was performed to identify studies reporting CPS and/or LMS-related complications. Complications were categorized into intraoperative and early postoperative (within 30 days of surgery) and late postoperative (after 30 days from surgery) complications. All studies that met the prespecified inclusion criteria were pooled and cumulatively analyzed. A total of 24 studies were conducted during the time frame of the search and comprising 1768 participants and 8636 subaxially placed screws met the inclusion criteria. The CPS group experienced significantly more postoperative C5 palsy (odds ratio OR = 3.48, 95% confidence interval CI = 1.27–9.53,
p
< 0.05). Otherwise, there were no significant differences between the LMS and CPS groups. There were no significant differences between the CPS and LMS groups in terms of neurovascular procedure-related complications other than significantly more C5 palsy in the CPS group.
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