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A new species, Polygala guilanica (Polygalaceae), is described from Kooh-Roubar, Gasht-Roodkhan protected area in W Guilan province, N Iran. The new species is distinguished based on its prostrate stem; small, lanceolate, ovate and rhombic, sessile leaves; tiny pink-white flowers in lax terminal racemes; 6 or 8 stamens with sessile anthers, a filiform style and brownish seed with 3-lobed caruncle. Detailed morphological description of the new species, photographs and distribution map are provided. Polygala guilanica is compared with the morphologically closest species: P. kurdica, P. hohenackeriana and P. anatolica. An updated identification key is provided for the Iranian species.

Pollen and seed micro-morphological features of six species of Polygala distributed in Iran were examined using light (LM) and scanning electron microscope (SEM). The results show a great pollen morphological variation, which provides helpful data for species delimitation in Polygala. The pollen grains are monad, radially symmetrical, isopolar, polyzonocolporate, medium to large, oblate-spheroidal to prolate-spheroidal in shape. We observed four types of surface sculpture (psilate, psilate to granulate, rugulate-granulate and rugulate) and four types of apocolpial area (psilate with small lumina, reticulate with large lumina, micro-perforate and coarsely regulate and gemmate or granulate with lumina). Moreover, the importance of seed micro-morphological traits in species delimitation have demonstrated based on elaiosome appendages size, number of lobes and their sculpture, seed surface sculpture and trichome type.

Early stage crystallization kinetics of polypropylene (PP)/clay composites is studied using rheometery. Relaxation modulus of composites is measured at low frequencies near liquid–solid transition. Small amplitude oscillating shear flow is applied at low frequencies to obtain relaxation modulus. Relaxation modulus of polymeric materials at the liquid–solid transition follows [Formula: see text], at long times ( λ < t < ∞), where λ is the time to crossover to a different relaxation regime, s is the gel stiffness, and n is the relaxation exponent. Inverse quenching technique is then employed to retain degree of crystallization while rheological measurements are made. Lower gel time is observed as clay concentration increased, indicating the formation of more nuclei. An improvement to Avrami’s equation is proposed to predict crystallization kinetics for PP/clay composites. There is a good agreement between predicted relative crystallinity values and empirical values.

ObjectiveThe only pharmacologic prophylaxis for cerebral vasospasm after subarachnoid hemorrhage is oral nimodipine. A novel way to mitigate this risk may be to design a drug eluting stent that elutes verapamil over the time period typically associated with vasospasm. In this study, we explore different methods of coating nitinol stents with a bioabsorbable polymer and determine the release profile of various verapamil coated stents for the potential treatment of vasospasm.MethodsNitinol stents were coated with different concentrations of poly(lactic acid-co-glycolic acid) (PLGA) in chloroform solution and using three coating techniques: dip coating, spin coating, and electrospinning. Morphology of the coatings were studied with scanning electron microscopy. 12 verapamil eluting stents were then prepared using different verapamil concentrations and coatings with different numbers of layers. Drug release behaviors were studied using UV spectroscopy for 21 days.ResultsElectrospinning at 20% w/v resulted in a smooth uniform coating without significant surface irregularities, and may be the most effective technique to coat stents. Stents with a single layer of PLGA/verapamil coating showed a two phase release profile (initial burst release followed by a slow rate of release) whereas stents with a bilayer coating showed a lower level of initial release followed by a slower sustained release phase.ConclusionsDevelopment of verapamil eluting stents that elute drug over the time course typical of cerebral vasospasm, and for either immediate or prophylactic treatment, is technically feasible. Further in vitro and in vivo studies are required to determine whether this can improve the outcome of patients after subarachnoid hemorrhage.

Selection of various grafts for anterior cruciate ligament (ACL) reconstructions have been employed in order to improve on stability and function of the knee. This study aimed to compare stability and function of the knee after ACL arthroscopic reconstruction by single-loop tibialis posterior (TP) allograft and four-strand hamstring tendon (HT) autograft. The retrospective cohort study included 104 patients in the TP group matched with 118 patients in the HT group in terms of demographic characteristics, associated meniscus injury, subjective and objective knee characteristics. All patients were followed up for at least three years with regards to mentioned criteria and time of return to former activities. The mean (range) age of TP (88 males and 16 females) and HT (99 males and 19 females) groups was 34.4 (19–48) and 36.9 (20–51) years, respectively. Median (range) follow-up durations were 55 (37–71) and 56 (36–72) months, respectively. No significant differences were observed post-operatively, regarding subjective and objective evaluations. Additionally, time duration for return to former activity was similar in both groups. Post-operative paresthesia and numbness of medial aspect of the calf were observed for two months in eight patients of the HT group which persisted to the final visit in one case. No similar symptom was seen in the TP group. In arthroscopic ACL reconstruction, fresh frozen doubled TP allograft compared to HT autograft was equally effective in restoring function and stability of knee, permitting return to former activities. Retrospective comparative, Level III

Background: Despite the introduction of different techniques for meniscal repair, no single procedure is superior in all situations. The new method for meniscal repair named “modified outside-in technique” aims to achieve higher primary fixation strength by an alternative suture technique as well as avoid disadvantages of outside-in, inside-out, and all-inside suture procedures. Additionally, the mid-term results of surgically treated patients with meniscal injuries by our new technique were evaluated. Methods: The current prospective study included 66 patients who underwent meniscal repair by the modified outside-in technique. The International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form was completed pre- and post-operatively. At final follow-up, Lysholm score was completed and patients were questioned about their return to previous sport activities. Clinical success was defined as lack of swelling and joint line tenderness, absence of locking, negative McMurray test and no need for meniscectomy. Patients’ satisfaction was evaluated using the visual analogue scale (VAS). Patients were followed for 26±1.7 months. Results: Clinical success was achieved in 61 patients (92.4%) and 5 candidates required meniscectomy (7.6%). IKDC Subjective Knee Evaluation Form score increased significantly from 54.2±12.7 preoperatively to 90.8±15.6 postoperatively (P

Conductive nanofibers of poly(vinylidene fluoride) (PVDF) filled with polyaniline (PANi)-coated multi-wall carbon nanotubes (MWCNTs) were fabricated using the electrospinning technique. PANi is an intrinsically conductive polymer. The addition of PANi-coated MWCNTs to PVDF created short conductive strands on the surface of the nanofibers, facilitating the formation of a conductive network in the transverse direction of the nanofibers. Piezoelectricity along with electric conductivity makes these PVDF nanofibers promising for applications such as sensors and actuators. Electrospun PVDF nanofiber mats had higher piezoelectricity than melt-processed samples produced using traditional polymer processing techniques, such as compression molding. Spectroscopic imaging techniques were employed to study the effects of the filler and processing conditions on the nanofiber structure. X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry results indicated a large increase in the β-phase crystals of the PVDF nanofibers. This higher content of β-phase crystals enhanced the piezoelectricity of the nanofibers. © 2015 Society of Chemical Industry

Multiwalled carbon nanotubes (MWCNTs) were introduced into poly(methyl methacrylate) (PMMA) and styrene-acrylonitrile copolymer (SAN) blends by melt mixing in an asymmetric miniature mixer (APAM). A composition of 70 wt% of PMMA and 30 wt% of SAN was mixed to create a co-continuous morphology. Transmission electron microscopy images of ultra-microtomed samples (70 nm in thickness) showed selective localization of MWCNTs inside the percolated SAN phase. The occurrence of the double percolation phenomenon resulted in lower electrical percolation thresholds of PMMA/SAN/MWCNT blends molded at high temperatures. Dielectric spectroscopy indicated a higher electrical permittivity for samples that were compression molded at 260°C. Due to the higher affinity of MWCNTs to SAN, there was a migration of MWCNTs into the SAN phase during the melt processing. Conductivity measurements revealed a significant decrease in electrical percolation threshold (0.4 wt%) for PMMA70/SAN30 blends compared with MWCNT-filled SAN and MWCNT-filled PMMA (ca. 0.8 wt%). POLYM. COMPOS., 2014. © 2014 Society of Plastics Engineers

Polyaniline (PANi)-coated multiwall carbon nanotubes (MWCNTs) and uncoated MWCNTs were added to a polystyrene (PS) matrix using solution and melt mixing. Electrical and rheological measurements were carried out on polymer composites to study the mechanism of conductive network formation. This work reveals the effect of nanofiller's coating on network formation using both rheological and electrical techniques. PANi-coated MWCNTs exhibit a much lower electrical percolation threshold (0.4 wt%) than uncoated MWCNTs (0.7 wt%), due to better dispersion of PANi-coated MWCNTs in a PS matrix. Dispersion of nanofillers in a polymer matrix was studied using optical microscopy and differential scanning calorimetry (DSC). Rheological characterizations of composite samples revealed a percolation behavior at higher concentration than that found electrical percolation. The inverse of damping factor ( G ′/ G ″) was the best parameter to elucidate the percolation threshold in a polymeric composite (i.e. PANi-coated MWCNT in PS had electrical percolation of 0.40 wt% and rheological percolation 0.52 wt%). A better affinity of PANi with PS led to better dispersion of nanofillers and lower rheological percolation for PS/MWCNT-PANi composites than those seen for PS/MWCNT composites.

In situ polymerization of aniline monomers in the presence of multiwall carbon nanotubes (MWCNTs) leads to core–shell nanostructures for use in conductive polymer composites. The conductivity of core–shell nanofibers can be tuned by altering coating thickness. These high-aspect-ratio MWCNT-polyaniline core–shell nanofibers are dispersed in polystyrene (PS) using solution mixing. These composites exhibit electrical percolation at a much lower concentration than MWCNT/PS composites. Polyaniline (PANi), when used as a coating layer, is able to attenuate electromagnetic (EM) waves via absorption. The dielectric measurements of MWCNT-PANi/PS composites show one order of magnitude increase in real electrical permittivity compared with that of MWCNT/PS composites, making them suitable for charge storage purposes.

Poly(vinylidene) fluoride (PVDF) nanocomposite samples were prepared by incorporation of carbon nanotubes (CNT) and nanoclay into PVDF using a twin screw extruder. Carbon nanotube was added to improve electrical conductivity and nanoclay was included to enhance β crystal formation for piezoelectric property. X-ray diffraction (XRD) results showed that partial melt intercalation of PVDF in clay was achieved. The XRD results also revealed that CNT and nanocaly addition increased β phase crystal amount in PVDF. FTIR spectroscopy measurements confirmed the XRD results and showed that the effect of nanoclay on β phase crystal formation of PVDF was more prominent than CNT. It was found that shear rate applied during crystallization would improve β phase crystal formation but only for the neat PVDF. Electrical conductivity results showed that addition of CNT improved conductivity as a percolation of 2 wt.% was observed. It was found that dispersion of CNT into PVDF matrix is very crucial for obtaining a higher conductivity. The results showed that clay incorporation into CNT nanocomposite improved electrical conductivity. The TEM micrographs showed bundles of CNT were adhered to clay particles. That was considered an indication of affinity between CNT and organically modified clay. The results of compounding of CNT and nanoclay with PVDF in batch mixer also revealed improvement in electrical conductivity when clay was added into PVDF/CNT composite in melt state. The conductivity improved with mixing time for both systems: PVDF/CNT and PVDF/CNT/nanocaly.