An in vitro release study of indomethacin from nanoparticles based on methyl methacrylate/glycidyl methacrylate copolymers

Indomethacin was coupled onto some macromolecular nanostructures based on methyl methacrylate copolymers with glycidyl methacrylate and tested as a model drug. The polymeric matrices were synthesized by radical emulsion copolymerization with and without the presence of a continuous external magnetic field of 1500 Gs intensity. Mathematical analysis of the release data was performed using Higuchi, Peppas–Korsmeyer equations. NIR chemical imaging (NIR-CI) was used to provide information about the spatial distribution of the components in the studied nanostructures. This opportunity was used to visualize the spatial distribution of bioactive substances (indomethacin) into the polymeric matrix, as well as to evaluate the degree of chemical and/or physical heterogeneity of the bioactive samples. The release rate dependence on the synthesis conditions as well as on the chemical compositions of the tested polymeric systems, it was also evidenced.     

Localization of Mn2+ ions in mesoporous NnS

Nanocrystalline cubic ZnS doped with 0.2% mol manganese, exhibiting a stable mesoporous structure, was synthesized at room temperature by a non toxic surfactant-assisted liquid-liquid reaction. The X-ray diffraction measurements demonstrate the formation of a sponge-like mesoporous material built from cubic ZnS nanocrystals of 1.8 nm average sizes, with a tight distribution of pores of 1.8 nm mean diameter. The transmission electron microscopy images confirm the formation of the mesoporous structure with walls of 3.1 nm mean thickness built from cubic ZnS nanocrystallites of 2.1 nm average size. The resulting tight distribution of crystallites and pores yields a well resolved Electron Paramagnetic Resonance spectrum, with the narrowest reported component lines attributed to three types of isolated Mn2+ centers, called Mn2+(I), Mn2+(II) and Mn2+(III). From the analysis of the spin Hamiltonian parameters it is shown that in the Mn2+(I) centers the paramagnetic ion is situated at substitutional Zn sites in the ZnS nanocrystals, being also subjected to a small axial distortion. The relative concentration changes under thermal treatment experiments strongly suggest that in both Mn2+(II) and Mn2+(III) centers the Mn2+ ion is localized on the surface of the ZnS nanocrystallites, being bond to an oxygen ion in the first case and to an additional water molecule in the second case.     

Upon some multi-membrane hydrogels based on poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) Undecane): preparation,characterization and in vivo tests

The study presents the possibility of preparation of multi-membrane gel systems with different morphologies and properties, based on poly(N,N-dimethyl-acrylamide-co-3,9-divinyl-2,4,8,10-tetraoxaspiro (5.5) undecane) copolymer and crosslinked with N,N′-methylene-bis-acrylamide. The basic copolymer has dual thermo- and pH sensitive character. After the core hydrogel is realized, the preformed gel is immersed in the aqueous solutions of ammonia, sodium chloride and sodium citrate for further edge constructing of the supramolecular assemblies. Then, the new layers by adding new sets of gelifying components are realized. The new multi-membrane gel systems are intended to be used as matrix for bioactive substances embedding. In this context the systems were loaded with norfloxacin as drug model. The in vivo tests show good biocompatibility for the implants based on multi-membrane gel structures loaded with drug.     

Remote‐controlled peristaltic locomotion in free‐floating pnipam hydrogels

Peristalsis‐driven locomotion, by nature of its flexibility and deformability, is a highly advantageous mechanism for mobility in soft materials and robots; however, utilization of this mechanism has been limited to restricted, frictional environments. (Seok et al., presented at 2010 IEEE International Conference on Robotics and Automation, Anchorage, AK May 3–8, 2010; Boxerbaum et al., Int J Robotics Res 2012, 31, 302; Boxerbaum et al., presented at 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems, San Francisco, CA, 2011; Arora et al., J Polym Sci Part A: Polym Chem 2009, 47, 5027). We have removed this limitation and expanded the use of peristaltic locomotion to open aqueous environments by remotely inducing peristalsis via spatially controlled volume phase transitions in thermosensitive poly(N‐isopropylacrylamide) (PNIPAM) hydrogels. The resulting asymmetry causes steady, incremental linear displacement in the hydrogel's center of mass, thus producing directed, remote‐controlled locomotion. In our proof‐of‐principle system, we controlled the peristaltic locomotion of the hydrogels using a handheld laser to selectively induce volume phase transitions in the hydrogel. The PNIPAM hydrogels' energy absorbance capability was enhanced by incorporating the New Indocyanine Green laser dye (IR‐820) into the gel. The use of IR‐820 is likely to expand the application space for these hydrogels due to new opportunities for conjugation chemistry. (Prajapati et al., Molecular Imaging 2009, 8, 45; Fernandez‐Fernandez et al., Molecular Imaging 2011, 11, 1). Overall, such an approach increases the capability of both peristaltic locomotion as a mechanism for mobility in soft robots, and PNIPAM hydrogels as a biotechnological platform. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40927.     

Discovering novel memory cell designs for sentiment analysis on tweets

Designing a Recurrent Neural Network to extract sentiment from tweets is a very hard task. When using memory cells in their design, the task becomes even harder due to the large number of design alternatives and the costly process of finding a performant design. In this paper we propose an original evolutionary algorithm to address the hard challenge of discovering novel Recurrent Neural Network memory cell designs for sentiment analysis on tweets. We used three different tasks to discover and evaluate the designs. We conducted experiments and the results show that the best obtained designs surpass the baselines—which are the most popular cells, LSTM and GRU. During the discovery process we evaluated roughly 17,000 cell designs. The selected winning candidate outperformed the others for the overall sentiment analysis problem, hence showing generality. We made the winner selection by using the cumulated accuracies on all three considered tasks.

     

Deposition of hydroxyapatite thin films by Nd:YAG laser ablation: a microstructural study

Hydroxyapatite (HA) thin films has been successfully deposited by Nd:YAG laser ablation at λ = 532 nm. The morphology and microstructure of the deposited layers was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution electron microscopy (HREM). Polycrystalline HA films were directly obtained with the substrate at 300 °C and without introducing water vapors in the deposition chamber. Electron paramagnetic resonance (EPR) measurements show that the oxygen stoichiometry in the HA films is also maintained. Depositions performed at λ = 335 nm laser wavelength and 300 °C substrate temperature resulted in polycrystalline layers of mixed composition of HA and tricalciumphosphate (TCP).     

Endoscopic projectile extraction in treatment of a gunshot injury to the head

HISTORY AND CLINICAL FINDINGS: A 14-year-old boy had in war-torn Bosnia sustained a transcranial gunshot wound from a 7.65 mm bullet. After primary medical care with craniotomy and the removal of bony fragments and cerebral debris followed by a duraplasty, he was transported to the French-German Field Hospital. On arrival he was breathing spontaneously and in stable cardiovascular state but with impaired responsiveness and somnolent. His pupils were moderately dilated with slight anisocoria (right > left). His gaze was deviated to the left and he had vertical gaze paralysis as well as right central facial nerve paresis. In addition he had a mild diencephalic syndrome, right hemiplegia and a right hemihypaesthesia with increased muscle tone, especially of the leg, paratonia and right positive Babinski reflex. There also was a marked ciliospinal reflex and he had a bulbar speech as well as cognitive and memory abnormalities. INVESTIGATIONS: Haemoglobin and haematocrit were below normal (12.1 g/dl and 35.0%, respectively), while biochemical tests were normal. Cranial computed tomography localized the bullet in the pineal recess of the 3rd ventricle and the lamina quadrigemina. DIAGNOSIS, TREATMENT AND COURSE: These findings indicated endoscopic transcranial removal of the bullet, achieved with a rigid endoscope and forceps along the entry track. Subsequent intensive care proceeded without complication. On discharge the boy was normal oriented and ready to make contact. The neurological defects were regressing. CONCLUSION: Endoscopic transcranial removal of a bullet wedged in the brain is a relatively sparing neurological procedure which, under unusual circumstances and conditions, can achieve a satisfactory result even with limited facilities.     

Growth of large ultratransparent KCl single crystals

This paper reports the successful realization and operation of an installation for growing single crystals of ultratransparent KCl by injecting the reactive atmosphere. The devised procedure and apparatus can be used for preparing on a reproducible basis large-single-crystalline ingots with bulk absorption at 10.6 μm approaching the intrinsic limit, as requested in high power laser applications.     

Oxidation of Steel Samples in Air Under the Action of a Photodissociative Iodine Laser

Abstract

We report experimental data on the oxidation of steel samples in air by laser irradiation using pulses of different duration generated by a photodissociative iodine laser source. The results indicate an enhancement of the oxidation process under the action of laser radiation as compared with conventional oxidation techniques.