1,4-D-Glucan block copolymers: synthesis and comprehensive structural characterization

Multi-block glucans comprising permethylated and partially methylated blocks are compounds of interest. In order to monitor their formation by transglycosylation of corresponding starting glucans, a method has been developed and applied to model compounds. This method allows determining the average length of the blocks and the progress of incorporation of methyl blocks in partially methylated sequences with a random distribution. The method, comprising liquid chromatography mass spectrometry (LC-MS) and electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MSn) measurements of two types of peralkylated glucans representing derivatives of the target compounds, is comprehensively described and discussed. ESI-MSn allows looking into the sequences of oligomeric domains. In addition, transglycosylation is followed by attenuated total reflection FTIR and NMR spectroscopy. Graphical abstract

Debenzylation of Benzyl-Protected Methylcellulose

Methyl cellulose and its derivatives are widely used in the food industry, cosmetics, and as construction materials. The properties of methyl celluloses (MC) strongly depend on their degrees and positions of substitution. In order to generate MCs with uncommon blocky substitution, we apply fully protected O -benzyl- O -methyl celluloses (BnMC). Such complex polysaccharide derivatives could not be deprotected completely and without shift of the composition by methods usually applied to mono- and oligosaccharides. Therefore, a facile debenzylation method was developed based on photo-initiated free-radical bromination in the presence of hydrobromic acid scavengers followed by alkaline treatment. The reaction proceeds under homogeneous conditions and without the aid of any catalyst. There is no need for expensive equipment, materials, anhydrous reagents, or running the reaction under anhydrous conditions. Reaction parameters were investigated and optimized for successful debenzylation of completely protected BnMC with degrees of methyl substitution (DS Me ) around 1.9 (and DS Bn around 1.1). Side-product-free and almost complete debenzylation was achieved when 1,2-epoxybutane (0.5 eq./eq. N -bromosuccinimide) and 2,6-di- tert -butylpyridine (0.5 eq./eq. N -bromosuccinimide) were used in the reaction. Furthermore, ATR-IR and 1 H NMR spectroscopy confirmed the successful removal of benzyl ether groups. The method was developed to monitor the transglycosylation reaction of the BnMC with permethylated cellulose, for which the deprotection of many small samples in parallel is required. This comprises the determination of the methyl pattern in the glucosyl units by gas-liquid chromatography (GLC), as well as oligosaccharide analysis by liquid chromatography mass spectrometry (LC-MS) after perdeuteromethylation and partial hydrolysis to determine the methyl pattern in the chains. The unavoidable partial chain degradation during debenzylation does not interfere with this analytical application, but, most importantly, the DS and the methyl pattern were almost congruent for the debenzylated product and the original MC, indicating the full success of this approach The presented method provides an unprecedented opportunity for high throughput and parallel debenzylation of complicated glucans, such as BnMC (as a model compound), for analytical purposes. For comparison, debenzylation using Na/NH 3 was applied to BnMC and resulted in a completely debenzylated product with a remarkably high recovery yield of 99 mol% and is, thus, the method of choice for synthetic applications, e.g., for the transglycosylation product prepared under the selected conditions in a preparative scale

Abnormal Visual Function: An Under-recognized Risk Factor of Road Traffic Injuries

Purpose: To determine the relationship between road accidents with visual acuity, refractive errors, visual field, and contrast sensitivity. Methods: This population-based case–control study was conducted on roads leading to Tehran Province, Iran. The case group comprised drivers who had met with accidents and were at fault for the accident. The cases were selected in an ongoing manner (incidence cases). The controls were drivers who were the opposing victims in the same. After an initial interview, optometric and ophthalmic examinations including the measurement of visual acuity, refraction, visual field assessment, contrast sensitivity measurement, and slit lamp biomicroscopy were performed for all study participants. Results: In this study, 281 and 204 individuals were selected for the case and control groups. The mean uncorrected visual acuity was 0.05 ± 0.12 and 0.037 ± 0.10 logMAR in the case and control groups, respectively (P = 0.095). Of the participants in the case and control groups, 32.8% and 23% had a visual field defect in at least one eye, respectively (adjusted odds ratios [aOR] = 1.63, 95% confidence interval [CI]: 1.08–2.48; P = 0.021). Moreover, 16.2% of the cases and 8.3% of the controls had visual field defects in both eyes (aOR = 2.13, 95% CI: 1.17–3.86; P = 0.012). Contrast sensitivity was worse in the case group in all spatial frequencies under non-glare conditions. However, under glare conditions, the contrast sensitivity was significantly worse in the case group only in the spatial frequency of 12 cycles per degree (cpd). Conclusion: Reduced contrast sensitivity, especially under non-glare conditions, and visual field defects are risk factors that influence the prevalence of road accidents. It is strongly advised that special attention be paid to these visual functions in legal assessments to apply the necessary interventions in individuals with these types of disorders

The prevalence of ptosis in an Iranian adult population

AbstractPurposeTo determine upper eyelid ptosis prevalence and some related factors in 44- to 69-year-olds of Shahroud in the north of Iran.MethodsIn 2009, using multi-stage cluster sampling, 300 clusters of 40–64-year-olds were selected in Shahroud city, and all 5190 participants were invited to be re-examined in 5 years (2014). The current report is the second phase of the study in which 4737 (91.3%) people participated and underwent vision tests, slit lamp examination, biometry, and ophthalmoscopy in 2014. Upper eyelid ptosis was determined by an ophthalmologist.ResultsThe prevalence of upper eyelid ptosis was 4.7% [95% confidence interval (CI): 4.1–5.4]; 5.2% in women and in 4.0% in men. The prevalence of bilateral and unilateral ptosis was 1.3% (95% CI: 1.0–1.7) and 3.4% (95% CI: 2.8–4.0), respectively. The observed prevalence of ptosis was 3.1% in the 45- to 49-year age group and 5.8% in 65- to 69-year-olds. The prevalence of ptosis increased with age. In the multiple logistic regression model, ptosis prevalence correlated with older age, diabetes (odds ratio = 1.53, 95% CI: 1.16–2.02) and hypertension (odds ratio = 1.41, 95% CI: 1.03–2.92). Mean corneal astigmatism was 1.02 (95%C]: 0.87–1.18) diopter in ptotic eyes and 0.87 (95% CI: 0.84–0.89) diopter in non-ptotic eyes (p = 0.013).ConclusionsThe present report provides valuable information on the prevalence of ptosis in a population of 45-to 69-year-olds. The prevalence of ptosis in this study was considerably high and significantly increased with age

Laboratory comparison of roller-compacted concrete and ordinary vibrated concrete for pavement structures

Kolnik od valjanog betona (RCCP) sastoji se od istih komponenata kao i kolnik od običnog vibriranog betona (NVC). U radu se analiziraju razlike između RCCP-a i NVC-a. Prikazi mikrostrukture pokazuju da RCCP ima veću gustoću pakiranja u usporedbi s uzorcima NVC. Vrijednosti tlačne čvrstoće nakon 28 dana, vlačne čvrstoće pri cijepanju i vlačna čvrstoća savijanjem RCCP-a veće su za 9 %, 4 % i 25 % od odgovarajućih čvrstoća NVC-a. Konačne vrijednosti kapilarnog upijanja i poroznosti RCCP-a otprilike su za 8 % tj. 10,6 % niže od odgovarajućih vrijednosti NVC-a.The roller-compacted concrete pavement (RCCP) has the same ingredients as the pavement made of normal vibrated concrete (NVC). Microstructure images show that RCCP has higher pack density compared to NVC specimens. The 28-day compressive, splitting tensile, and flexural strengths of RCCP are by 9%, 4%, and 25% higher than those of NVC. The final water absorption and porosity values are by about 8% and 10.6% lower for RCCP in comparison with NVC

High Prevalence of Asthenopia among a Population of University Students

Purpose: To determine the prevalence of asthenopia and its associated factors in a sample of university students in Iran. Methods: In this cross-sectional study, participants were selected using multistage cluster sampling. Presence of at least one of the 10 symptoms—foreign body sensation, diplopia, blurred vision, eye swelling, dry eye, eye pain, difficulty in sustaining visual operations, decreased visual acuity, tearing, and photophobia—was considered as asthenopia. Ocular examinations, including uncorrected/corrected visual acuity measurement, objective/subjective refraction, cover test, amplitude of accommodation (AA), and near point of convergence (NPC) were performed. Results: Of the 1,462 students (mean age: 22.8 ± 3.1 years), 73% were women. The age- and gender standardized prevalence was 70.9% (95% confidence interval [CI]: 68.3–73.5), 39.8% (95% CI: 36.4–43.1), and 19.7% (95% CI: 16.0–23.3) based on the presence of at least one, two, and three symptoms, respectively. The prevalence was significantly higher in females (P = 0.048), hyperopic students (P < 0.001), and astigmatic participants (P < 0.001). The mean AA and NPC were 9.7 ± 2.6 D and 10.2 ± 4.2 D (P = 0.008) and 7.0 ± 2.1 cm and 7.7 ± 3.9 cm (P < 0.001) in participants with and without asthenopia, respectively. Multiple regression model revealed age (28–29 years), astigmatism, and NPC as independent associated factors (odds ratios: 3.51, 1.61, and 0.91, respectively). Conclusion: This study shows relatively high prevalence of asthenopia in university students. Demographic factors and visual system disorders are important risk factors and timely correction of conditions may lead to decreased asthenopia

P100 Wave Latency and Amplitude in Visual Evoked Potential Records in Different Visual Quadrants of Normal Individuals

Purpose: Assessment of the pattern visual evoked potential (PVEP) responses in different areas of visual fields in individuals with normal vision. Methods: This study was conducted on 80 eyes of normal subjects aged 18–35 years. All participants underwent refraction and visual acuity examination. Visual evoked potential (VEP) responses were recorded in different areas of field. The repeated measure test was used to compare the P100 latency and amplitude of PVEP among different areas. Results: The repeated measures analysis of variance showed a statistically significant difference among different areas in terms of amplitude and latency of P100 (P = 0.002 and P < 0.001, respectively). According to the results, the highest and lowest amplitude of P100 was observed in inferior-nasal and superior areas, respectively. The highest and lowest latency of P100 was related to the temporal and inferior-nasal areas, respectively. Conclusion: This study partially revealed the details of local PVEP distribution in the visual field and there was a significant difference in the amplitude and latency of PVEP wave in different areas of the visual field

Evaluation of lentiviral vector-based green fluorescent protein expression in human gastric cancer cell line evaluation of expression lentivirus vector-based GFP in AGS

Background and aims : Human immunodeficiency virus type 1 (HIV-1) based-lentivirus vector is one of the most promising viral vectors for gene delivery in different cell lines including gastric cell lines. Therefore, the aim of this study was to produce a lentivirus vector for transduction and expression of green fluorescent protein (GFP) in human gastric cancer cell line, AGS. Materials and Methods: In this piece of work, Escherichia coli HB101 was transformed with plasmids psPAX2, pTD, and pMD2.G, following the purification of which their DNA was extracted along with their quantity and quality evaluated to be used in the next experiments. Subsequently, to produce the vector, the packaging cells were transfected with the plasmids and the vector containing supernatant was collected and purified using ultracentrifuge. ELISA was used to confirm the construction of the vector. Fluorescent microscopy and flow cytometry were used to check the expression of GFP in the cell line and to calculate the percentage of GFP expression, respectively. Results: In this study, the results of ELISA confirmed the construction of the plasmid used in this study. AGS cells were infected with viruses produced to detect the viral activity and GFP expression was evaluated by fluorescence microscopy and flow cytometry after 72 hours. Based on the results of flow cytometry, GFP was expressed in over 90% of transduced AGS cells. Conclusion: The results of this study showed that lentiviral vector is a highly efficient vector for expression of GFP gene in AGS cell line. Keywords: Lentivirus-based vector, Transfection, Transduction, GFP, AG

Ultrathin positively charged electrode skin for durable anion-intercalation battery chemistries

The anion-intercalation chemistries of graphite have the potential to construct batteries with promising energy and power breakthroughs. Here, we report the use of an ultrathin, positively charged two-dimensional poly(pyridinium salt) membrane (C2DP) as the graphite electrode skin to overcome the critical durability problem. Large-area C2DP enables the conformal coating on the graphite electrode, remarkably alleviating the electrolyte. Meanwhile, the dense face-on oriented single crystals with ultrathin thickness and cationic backbones allow C2DP with high anion-transport capability and selectivity. Such desirable anion-transport properties of C2DP prevent the cation/solvent co-intercalation into the graphite electrode and suppress the consequent structure collapse. An impressive PF6−-intercalation durability is demonstrated for the C2DP-covered graphite electrode, with capacity retention of 92.8% after 1000 cycles at 1 C and Coulombic efficiencies of > 99%. The feasibility of constructing artificial ion-regulating electrode skins with precisely customized two-dimensional polymers offers viable means to promote problematic battery chemistries

Ultrathin positively charged electrode skin for durable anion-intercalation battery chemistries

The anion-intercalation chemistries of graphite have the potential to construct batteries with promising energy and power breakthroughs. Here, we report the use of an ultrathin, positively charged two-dimensional poly(pyridinium salt) membrane (C2DP) as the graphite electrode skin to overcome the critical durability problem. Large-area C2DP enables the conformal coating on the graphite electrode, remarkably alleviating the electrolyte. Meanwhile, the dense face-on oriented single crystals with ultrathin thickness and cationic backbones allow C2DP with high anion-transport capability and selectivity. Such desirable anion-transport properties of C2DP prevent the cation/solvent co-intercalation into the graphite electrode and suppress the consequent structure collapse. An impressive PF6−-intercalation durability is demonstrated for the C2DP-covered graphite electrode, with capacity retention of 92.8% after 1000 cycles at 1 C and Coulombic efficiencies of > 99%. The feasibility of constructing artificial ion-regulating electrode skins with precisely customized two-dimensional polymers offers viable means to promote problematic battery chemistries