Sestava, lastnosti, uporaba in reciklaža Kerrocka

Kerrock is a solid surface composite material, which is composed of 40 wt.% of polymethylmethacrylate (PMMA) and 60 wt.% of aluminium trihydroxide (ATH) filler with silane as a coupling agent. Similar material is also called PMMA/ATH composite in the academic literature, while Kerrock is one of its commercial names. PMMA is a hard material that is water- and UV-resistant and easy to work with, although its characteristics depend on the degree and process of polymerization that occurs. ATH is a white, nontoxic material that is relatively soft and non-abrasive. It is widely used as an effective fire-retardant filler in polymer composites. Because of its composition, the machining of Kerrock is similar to the machining of wood. Moreover, it can also be thermoformed, like thermoplastics. Kerrock is widely used for work surfaces and cladding, with both indoor and outdoor applications. The material’s interfacial morphology, interfacial adhesion between the filler and polymer matrix, dispersion of ATH particles and concentration of adhesion promoting agent have the biggest impacts on the mechanical characteristics of Kerrock. While it is possible to chemically recycle Kerrock, the energy required for this is too high for this process to be practical. Another option for recycling this composite is to combine its particles in a hot press or to add MMA or polyester resin before pressing. However, there remains much work to be done with regard to effectively recycling Kerrock

Frequency drift in MR spectroscopy at 3T

Purpose: Heating of gradient coils and passive shim components is a common cause of instability in the B-0 field, especially when gradient intensive sequences are used. The aim of the study was to set a benchmark for typical drift encountered during MR spectroscopy (MRS) to assess the need for real-time field-frequency locking on MRI scanners by comparing field drift data from a large number of sites.Method: A standardized protocol was developed for 80 participating sites using 99 3T MR scanners from 3 major vendors. Phantom water signals were acquired before and after an EPI sequence. The protocol consisted of: minimal preparatory imaging; a short pre-fMRI PRESS; a ten-minute fMRI acquisition; and a long post-fMRI PRESS acquisition. Both pre- and post-fMRI PRESS were non-water suppressed. Real-time frequency stabilization/adjustment was switched off when appropriate. Sixty scanners repeated the protocol for a second dataset. In addition, a three-hour post-fMRI MRS acquisition was performed at one site to observe change of gradient temperature and drift rate. Spectral analysis was performed using MATLAB. Frequency drift in pre-fMRI PRESS data were compared with the first 5:20 minutes and the full 30:00 minutes of data after fMRI. Median (interquartile range) drifts were measured and showed in violin plot. Paired t-tests were performed to compare frequency drift pre- and post-fMRI. A simulated in vivo spectrum was generated using FID-A to visualize the effect of the observed frequency drifts. The simulated spectrum was convolved with the frequency trace for the most extreme cases. Impacts of frequency drifts on NAA and GABA were also simulated as a function of linear drift. Data from the repeated protocol were compared with the corresponding first dataset using Pearson's and intraclass correlation coefficients (ICC).Results: Of the data collected from 99 scanners, 4 were excluded due to various reasons. Thus, data from 95 scanners were ultimately analyzed. For the first 5:20 min (64 transients), median (interquartile range) drift was 0.44 (1.29) Hz before fMRI and 0.83 (1.29) Hz after. This increased to 3.15 (4.02) Hz for the full 30 min (360 transients) run. Average drift rates were 0.29 Hz/min before fMRI and 0.43 Hz/min after. Paired t-tests indicated that drift increased after fMRI, as expected (p &lt; 0.05). Simulated spectra convolved with the frequency drift showed that the intensity of the NAA singlet was reduced by up to 26%, 44 % and 18% for GE, Philips and Siemens scanners after fMRI, respectively. ICCs indicated good agreement between datasets acquired on separate days. The single site long acquisition showed drift rate was reduced to 0.03 Hz/min approximately three hours after fMRI.Discussion: This study analyzed frequency drift data from 95 3T MRI scanners. Median levels of drift were relatively low (5-min average under 1 Hz), but the most extreme cases suffered from higher levels of drift. The extent of drift varied across scanners which both linear and nonlinear drifts were observed.</p

Model of mobile devices and privacy with Mobile Iron

Industrija pametnih mobilnih naprav je zadnje čase ena najbolj rastočih industrij na svetu. Ogromni potencial, ki ga ima mobilna tehnologija, bo za uporabnike najbolj vidna sprememba v načinu uporabe njihove mobilne naprave. To ne bo več samo naprava za pogovarjanje in pisanje kratkih sporočil, ampak za mnoge celo edini računalnik, ki bo v stalni uporabi. Mobilna tehnologija omogoča hiter in varen dostop do poslovnih podatkov v zalednem informacijskem sistemu organizacije ter enostaven dostop do virov informacij in storitev na internetu. S širjenjem pametnih mobilnih naprav in drugih prenosnih tehnologij postajata zasebnost in varnost vse bolj pomembni področji raziskovanja, upravljanja in omejevanja. Ozaveščanje zaposlenih na področju uporabe mobilne tehnologije je ključnega pomena. Le dobro usposobljen in ozaveščen zaposleni lahko izpolni pričakovanja odgovorne uporabe mobilne naprave. Dinamičen razvoj tehnologije, zahteve uporabnikov, hitre spremembe na pravem področju in kompleksnost sistemov zahtevajo ustrezno znanje. Tehnološke rešitve za upravljanje mobilne tehnologije v organizaciji morajo zagotavljati zaupnost, integriteto in dostopnost vseh komponent informacijskega sistema in naprav, ki se vanj povezujejo. Pri celovitem upravljanju mobilne tehnologije mora organizacija gojiti kulturo zasebnosti, ki je opredeljena v notranjih pravilih in aktih organizacije.The industry of smart mobile devices is one of the fastest growing industries in today\u27s world. The enormous potential of the mobile technology is likely to become the most visible change in the way the users deal with their mobile devices. It is no longer just a device for talking and writing short messages since for many it will soon become the only computer in constant use. Mobile technology enables fast and secure accesses to corporate data in the back-end of information systems and easy accesses to information resources and services on the Internet. With the proliferation of smart mobile devices and other portable technologies, privacy and security are becoming increasingly important areas of research, management and mitigation. Raising the awareness of employees in the use of mobile technology is crucial. Only the well-trained and informed employees can fulfill expectations of a responsible use of mobile devices. The dynamic development of technology, user requirements, rapid changes in laws and the complexity of systems require appropriate knowledge. Technological solutions for the management of mobile technology in the organization must ensure the confidentiality, integrity and availability of all information system components and devices that connect to it. For an integrated management of mobile technology the organization must cultivate a culture of privacy, defined in the internal rules and acts of the organization itself

Compatibility of wood with a composite from polymethyl methacrylate and aluminium hydroxide

Združljivost lesa s kompozitom iz polimetilmetakrilata in aluminijevega hidroksid

Composition, properties and application of Kerrock

Kerrock je trd kompozitni material, sestavljen iz 40 ut. % polimetil metakrilata (PMMA) in 60 ut. % aluminijevega hidroksida (ATH), vezni člen med njima pa je silan. V tuji strokovni literaturi podobne materiale poimenujejo kot PMMA/ATH kompozit, Kerrock pa je eno od komercialnih imen za ta material. Lastnosti PMMA so odvisne od stopnje in načina polimerizacije, na splošno pa velja, da je trd, vodoodporen in UV odporen ter se ga lahko obdeluje. ATH je bel, netoksičen material, relativno mehak in neabraziven ter eden izmed najbolj razširjenih samougasljivih dodatkov v polimernih kompozitih. Zaradi takšne sestave je Kerrock možno obdelovati kot les in ga termoformirati kot plastomerne materiale. Uporablja se za opremo notranjih prostorov in v gradbeništvu kot fasadni element. Na mehanske lastnosti vplivajo morfologija stičnih površin polnila, adhezija na stični površini med polnilom in polimerno matrico, porazdelitev delcev ATH in vsebnost silana oziroma drugih dodatkov. Kerrock je možno kemično reciklirati, vendar takšni postopki zahtevajo velik energijski vložek. Druga možnost recikliranja je povezovanje prašnih delcev Kerrocka z vročim stiskanjem in tudi možnim predhodnim dodajanjem MMA ali poliestrske smole. V zadnjih letih so se raziskave in razvoj reciklaže odpadnih produktov Kerrocka preusmerile v povezovanje le-teh z lesom, kar je privedlo do novih rešitev. Recikliranju tega kompozita bo v prihodnje potrebno posvetiti več pozornostiKerrock is a solid surface composite material, which is composed of 40 wt.% of polymethylmethacrylate (PMMA) and 60 wt.% of aluminium trihydroxide (ATH) filler with silane as a coupling agent. Similar material is also called PMMA/ATH composite in the academic literature, while Kerrock is one of its commercial names. PMMA is a hard material that is water- and UV-resistant and easy to work with, although its characteristics depend on the degree and process of polymerization that occurs. ATH is a white, nontoxic material that is relatively soft and non-abrasive. It is widely used as an effective fire-retardant filler in polymer composites. Because of its composition, the machining of Kerrock is similar to the machining of wood. Moreover, it can also be thermoformed, like thermoplastics. Kerrock is widely used for work surfaces and cladding, with both indoor and outdoor applications. The material%s interfacial morphology, interfacial adhesion between the filler and polymer matrix, dispersion of ATH particles and concentration of adhesion promoting agent have the biggest impacts on the mechanical characteristics of Kerrock. While it is possible to chemically recycle Kerrock, the energy required for this is too high for this process to be practical. Another option for recycling this composite is to combine its particles in a hot press or to add MMA or polyester resin before pressing. However, there remains much work to be done with regard to effectively recycling Kerroc

Semi-automatic signature-based segmentation method for quantification of neuromelanin in substantia nigra

In Parkinson\u27s disease (PD), there is a reduction of neuromelanin (NM) in the substantia nigra (SN). Manual quantification of the NM volume in the SN is unpractical and time-consumingtherefore, we aimed to quantify NM in the SN with a novel semi-automatic segmentation method. Twenty patients with PD and twelve healthy subjects (HC) were included in this study. T1-weighted spectral pre-saturation with inversion recovery (SPIR) images were acquired on a 3T scanner. Manual and semi-automatic atlas-free local statistics signature-based segmentations measured the surface and volume of SN, respectively. Midbrain volume (MV) was calculated to normalize the data. Receiver operating characteristic (ROC) analysis was performed to determine the sensitivity and specificity of both methods. PD patients had significantly lower SN mean surface (37.7 ± 8.0 vs. 56.9 ± 6.6 mm$^2$) and volume (235.1 ± 45.4 vs. 382.9 ± 100.5 mm$^3$) than HC. After normalization with MV, the difference remained significant. For surface, sensitivity and specificity were 91.7 and 95 percent, respectively. For volume, sensitivity and specificity were 91.7 and 90 percent, respectively. Manual and semi-automatic segmentation methods of the SN reliably distinguished between PD patients and HC. ROC analysis shows the high sensitivity and specificity of both methods

Review article: structural brain alterations in prelingually deaf

Functional studies show that our brain has a remarkable ability to reorganize itself in the absence of one or more sensory modalities. In this review, we gathered all the available articles investigating structural alterations in congenitally deaf subjects. Some concentrated only on specific regions of interest (e.g., auditory areas), while others examined the whole brain. The majority of structural alterations were observed in the auditory white matter and were more pronounced in the right hemisphere. A decreased white matter volume or fractional anisotropy in the auditory areas were the most common findings in congenitally deaf subjects. Only a few studies observed alterations in the auditory grey matter. Preservation of the grey matter might be due to the cross-modal plasticity as well as due to the lack of sensitivity of methods used for microstructural alterations of grey matter. Structural alterations were also observed in the frontal, visual, and other cerebral regions as well as in the cerebellum. The observed structural brain alterations in the deaf can probably be attributed mainly to the cross-modal plasticity in the absence of sound input and use of sign instead of spoken language

Assessment of short-term effect of platelet-rich plasma treatment of tendinosis using texture analysis of ultrasound images

Computer-aided diagnosis (i.e., texture analyses) tools are becoming increasingly beneficial methods to monitor subtle tissue changes. The aim of this pilot study was to investigate short-term effect of platelet rich plasma (PRP) treatment in supraspinatus and common extensor of the forearm tendinosis by using texture analysis of ultrasound (US) images as well as by clinical questionnaires