Fabrication of Conductive, High Strength and Electromagnetic Interference (EMI) Shielded Green Composites Based on Waste Materials.

Conventional conductive homopolymers such as polypyrrole and poly-3,4-ethylenedioxythiophene (PEDOT) have poor mechanical properties, for the solution to this problem, we tried to construct hybrid composites with higher electrical properties coupled with high mechanical strength. For this purpose, Kevlar fibrous waste, conductive carbon particles, and epoxy were used to make the conductive composites. Kevlar waste was used to accomplish the need for economics and to enhance the mechanical properties. At first, Kevlar fibrous waste was converted into a nonwoven web and subjected to different pretreatments (chemical, plasma) to enhance the bonding between fiber-matrix interfaces. Similarly, conductive carbon particles were converted into nanofillers by the action of ball milling to make them homogeneous in size and structure. The size and morphological structures of ball-milled particles were analyzed by Malvern zetasizer and scanning electron microscopy. In the second phase of the study, the conductive paste was made by adding the different concentrations of ball-milled carbon particles into green epoxy. Subsequently, composite samples were fabricated via a combination of prepared conductive pastes and a pretreated Kevlar fibers web. The influence of different concentrations of carbon particles into green epoxy resin for electrical conductivity was studied. Additionally, the electrical conductivity and electromagnetic shielding ability of conductive composites were analyzed. The waveguide method at high frequency (i.e., at 2.45 GHz) was used to investigate the EMI shielding. Furthermore, the joule heating response was studied by measuring the change in temperature at the surface of the conductive composite samples, while applying a different range of voltages. The maximum temperature of 55 °C was observed when the applied voltage was 10 V. Moreover, to estimate the durability and activity in service the ageing performance (mechanical strength and moisture regain) of developed composite samples were also analyzed.

Development of Novel Antimicrobial and Antiviral Green Synthesized Silver Nanocomposites for the Visual Detection of Fe3+ Ions.

In the current research, we present a single-step, one-pot, room temperature green synthesis approach for the development of functional poly(tannic acid)-based silver nanocomposites. Silver nanocomposites were synthesized using only tannic acid (plant polyphenol) as a reducing and capping agent. At room temperature and under mildly alkaline conditions, tannic acid reduces the silver salt into nanoparticles. Tannic acid undergoes oxidation and self-polymerization before the encapsulating of the synthesized silver nanoparticle and forms silver nanocomposites with a thick capping layer of poly(tannic acid). No organic solvents, special instruments, or toxic chemicals were used during the synthesis process. The results for the silver nanocomposites prepared under optimum conditions confirmed the successful synthesis of nearly spherical and fine nanocomposites (10.61 ± 1.55 nm) with a thick capping layer of poly(tannic acid) (~3 nm). With these nanocomposites, iron could be detected without any special instrument or technique. It was also demonstrated that, in the presence of Fe3+ ions (visual detection limit ~20 µM), nanocomposites aggregated using the coordination chemistry and exhibited visible color change. Ultraviolet-visible (UV-vis) and scanning electron microscopy (SEM) analysis also confirmed the formation of aggregate after the addition of the analyte in the detection system (colored nanocomposites). The unique analytic performance, simplicity, and ease of synthesis of the developed functional nanocomposites make them suitable for large-scale applications, especially in the fields of medical, sensing, and environmental monitoring. For the medical application, it is shown that synthesized nanocomposites can strongly inhibit the growth of Escherichia coli and Staphylococcus aureus. Furthermore, the particles also exhibit very good antifungal and antiviral activity.

Single-Step Green Synthesis of Highly Concentrated and Stable Colloidal Dispersion of Core-Shell Silver Nanoparticles and Their Antimicrobial and Ultra-High Catalytic Properties.

The versatile one-pot green synthesis of a highly concentrated and stable colloidal dispersion of silver nanoparticles (Ag NPs) was carried out using the self-assembled tannic acid without using any other hazardous chemicals. Tannic acid (Plant-based polyphenol) was used as a reducing and stabilizing agent for silver nitrate in a mild alkaline condition. The synthesized Ag NPs were characterized for their concentration, capping, size distribution, and shape. The experimental results confirmed the successful synthesis of nearly spherical and highly concentrated (2281 ppm) Ag NPs, capped with poly-tannic acid (Ag NPs-PTA). The average particle size of Ag NPs-PTA was found to be 9.90 ± 1.60 nm. The colloidal dispersion of synthesized nanoparticles was observed to be stable for more than 15 months in the ambient environment (25 °C, 65% relative humidity). The synthesized AgNPs-PTA showed an effective antimicrobial activity against Staphylococcus Aureus (ZOI 3.0 mM) and Escherichia coli (ZOI 3.5 mM). Ag NPs-PTA also exhibited enhanced catalytic properties. It reduces 4-nitrophenol into 4-aminophenol in the presence of NaBH4 with a normalized rate constant (Knor = K/m) of 615.04 mL·s-1·mg-1. For comparison, bare Ag NPs show catalytic activity with a normalized rate constant of 139.78 mL·s-1·mg-1. Furthermore, AgNPs-PTA were stable for more than 15 months under ambient conditions. The ultra-high catalytic and good antimicrobial properties can be attributed to the fine size and good aqueous stability of Ag NPs-PTA. The unique core-shell structure and ease of synthesis render the synthesized nanoparticles superior to others, with potential for large-scale applications, especially in the field of catalysis and medical.

Multifunctional self-assembled peptide nanoparticles for multimodal imaging-guided enhanced theranostic applications against glioblastoma multiforme.

The synthesis of self-assembled peptide nanoparticles using a facile one-pot synthesis approach is gaining increasing attention, allowing therapy in combination with diagnosis. Their drawback is limited diagnostic potential, which can be improved after necessary modifications and efficacious functionalization. Herein, a cyclic heptapeptide having the Arg-Gly-Asp-Lys-Leu-Ala-Lys sequence was modified by conjugation of the ε-amino group of the terminal lysine residue with diethylenetriamine pentaacetic acid (DTPA) as a bifunctional chelating agent (BFC) for radiolabeling with a γ-emitting radionuclide (99mTc, half-life 6.01 h; energy 140 keV). Further, the free amino group of the middle lysine residue was successfully conjugated with near-infrared fluorescence (NIRF) dye Cyanine5.5 N-succinimidyl ester (Ex/Em = 670/701 nm) by a co-assembly method to form newly designed novel NIRF dye conjugated self-assembled peptide-DTPA (Cy5.5@SAPD) nanoparticles. The fluorescent nanoparticle formation was confirmed by using a fluorescence spectrophotometer (Ex/Em = 650/701 nm), and the transmission electron microscope (TEM) images showed a size of ∼ 40 nm with a lattice fringe distance of 0.294 nm. Cytotoxicity and confocal laser scanning microscopy (CLSM) studies showed that these nanoparticles possess a high affinity for the αvß3-integrin receptor overexpressed on brain tumor glioblastoma with an EC50 = 20 µM. Moreover, these nanoparticles were observed to have potential to internalize into U87MG cells more prominently than HEK-293 cancer cells and induce apoptosis. The apoptosis assay showed 79.5% apoptotic cells after 24 h treatment of Cy5.5@SAPD nanoparticles. Additionally, these nanoparticles were also radiolabeled with 99mTc for the single photon emission computed tomography (SPECT) imaging study in tumor-bearing female Balb/c mice. The excellent imaging feature of Cy5.5@SAPD-99mTc nanoparticles as a multimodal (SPECT/NIRF) diagnostic probe, as well as noteworthy therapeutic potential was observed. The results suggested that our newly designed novel dual-targeting dual-imaging nanoparticles may serve as an admirable theranostic probe to treat brain tumor glioblastoma multiforme.

Molecular epidemiology and surveillance of circulating rotavirus among children with gastroenteritis in Bangladesh during 2014-2019.

Acute gastroenteritis is one of the major health problems in children aged <5 years around the world. Rotavirus A (RVA) is an important pathogen of acute gastroenteritis. The burden of rotavirus disease in the pediatric population is still high in Bangladesh. This study investigated the prevalence of group A, B, and C rotavirus (RAV, RBV, RCV), norovirus, adenovirus (AdV) and human bocavirus (HBoV) infections in children with acute gastroenteritis in Bangladesh from February 2014 to January 2019. A total of 574 fecal specimens collected from children with diarrhea in Bangladesh during the period of February 2014-January 2019 were examined for RAV, RBV and RCV by reverse transcriptase- multiplex polymerase chain reaction (RT- multiplex PCR). RAV was further characterized to G-typing and P-typing by RT-multiplex PCR and sequencing method. It was found that 24.4% (140 of 574) fecal specimens were positive for RVA followed by AdV of 4.5%. RBV and RCV could not be detected in this study. Genotype G1P[8] was the most prevalent (43%), followed by G2P[4] (18%), and G9P[8] (3%). Among other genotypes, G9P[4] was most frequent (12%), followed by G1P[6] (11%), G9P[6] (3%), and G11P[25] (3%). We found that 7% RVA were nontypeable. Mutations at antigenic regions of the VP7 gene were detected in G1P[8] and G2P[4] strains. Incidence of rotavirus infection had the highest peak (58.6%) during November to February with diarrhea (90.7%) as the most common symptom. Children aged 4-11 months had the highest rotavirus infection percentage (37.9%). By providing baseline data, this study helps to assess efficacy of currently available RVA vaccine. This study revealed a high RVA detection rate, supporting health authorities in planning strategies such as introduction of RVA vaccine in national immunization program to reduce the disease burden.

Silk fibroin nanoscaffolds for neural tissue engineering.

The nervous system is a crucial component of the body and damages to this system, either by injury or disease, can result in serious or potentially lethal consequences. An important problem in neural engineering is how we can stimulate the regeneration of damaged nervous tissue given its complex physiology and limited regenerative capacity. To regenerate damaged nervous tissue, this study electrospun three-dimensional nanoscaffolds (3DNSs) from a biomaterial blend of silk fibroin (SF), polyethylene glycol (PEG), and polyvinyl alcohol (PVA). The 3DNSs were characterised to ascertain their potential suitability for direct implant into the CNS. The biological activity of 3DNSs was investigated in vitro using PC12 cells and their effects on reactive astrogliosis were assessed in vivo using a photothrombotic model of ischaemic stroke in mice. Results showed that the concentration of SF directly affected the mechanical characteristics and internal structure of the 3DNSs, with formulations presenting as either a gel-like structure (SF ≥ 50%) or a nanofibrous structure (SF ≤ 40%). In vitro assessment revealed increased cell viability in the presence of the 3DNSs and in vivo assessment resulted in a significant decrease in glial fibrillary acidic protein (GFAP) expression in the peri-infarct region (p < 0.001 for F2 and p < 0.05 for F4) after stroke, suggesting that 3DNSs could be suppressing reactive astrogliosis. The findings enhanced our understanding of physiochemical interactions between SF, PEG, and PVA, and elucidated the potential of 3DNSs as a potential therapeutic approach to stroke recovery, especially if these are used in conjunction with drug or cell treatment.

Molecular and epidemiological trends of human bocavirus and adenovirus in children with acute gastroenteritis in Bangladesh during 2015 to 2019.

Virus associated diarrhea remains one of the leading causes of children morbidity and mortality in Bangladesh. Human bocavirus (HBoV) has been reported as a potential pathogen of children's diarrhea worldwide. However, due to its frequent association with other gastroenteric pathogens, its role as diarrhea causative agent remains to be defined. This study focuses to detect the incidence of HBoV and adenovirus (AdV) and to determine the molecular and epidemiological characteristics of HBoV and AdV. Between January 2015 to January 2019, 290 fecal specimens were collected from diarrheal children in Bangladesh. All fecal specimens were tested for HBoV and AdV by conventional polymerase chain reaction and sequencing methods. HBoV was detected in 7.24% (21 of 290) of the stool samples, as a sole virus in 71.42% (15 of 21) of the positive samples. AdV was detected in 4.82% (14 of 290) of the samples. The most common clinical symptoms of HBoV infected patients were diarrhea (100%) and vomiting (57%). All of the isolates of HBoV were from HBoV1 and AdV were from AdV41, AdV5, AdV7, and AdV8. To the best of our knowledge, this is the first epidemiological and molecular analysis report of HBoV from clinical specimens in Bangladesh. In the future, more studies are needed to clarify the role of HBoV as diarrheal pathogens.

Molecular and Epidemiologic Analysis of Diarrheal Pathogens in Children With Acute Gastroenteritis in Bangladesh During 2014-2019.

BACKGROUND: Diarrheal disease is one of the leading causes of childhood morbidity and mortality in the 21st century in developing countries. Mainly infants and young children develop diarrheal diseases. This study aims to determine the incidence of diarrheal pathogens in children in Bangladesh. METHODS: During 2014 to 2019, 387 fecal specimens were collected from children with diarrhea in Bangladesh. Bacterial pathogens were detected by conventional bacteriologic, biochemical and molecular sequence analysis methods. DNA virus and RNA virus (diarrheal viruses) were detected using polymerase chain reaction and reverse transcriptase polymerase chain reaction, respectively and confirmed by molecular sequence analysis. RESULTS: Bacterial infections were detected in 39.27% (152 of 387) of the stool samples. Escherichia coli was the most prevalent (17.3%) followed by Vibrio cholerae (13.5%), Salmonella spp. (4.9%) and Shigella spp. (3.6%). From 387 fecal specimens tested, 42.4% (164 of 387) were positive for viral infections. Rotavirus was the most prevalent (26.3%), followed by adenovirus (5.7%), norovirus (5.4%) and human bocavirus (4.9%). Dual infection between rotavirus and E. coli accounted for the largest portion of coinfection (48%). Diarrhea (77%) and abdominal pain (65%) were most common followed by vomiting (63%), fever (43%) and dehydration (39%). E. coli and V. cholerae were most resistant against ciprofloxacin (62.7%) and tetracycline (88.5%). qnrA and sul4 resistance genes were isolated from these pathogens. CONCLUSIONS: Data from this study underline the high incidence of diarrheal pathogens and presence of antibiotics resistance genes in a pediatric population in Bangladesh.

Detection, quantification and genotype distribution of HCV patients in Lahore, Pakistan by real-time PCR.

BACKGROUND: Hepatitis C virus (HCV) is considered as "Viral Time Bomb" suggested by the World Health Organization and if it is not treated timely, it will lead towards cirrhosis and hepatocellular carcinoma (HCC). OBJECTIVE: The purpose of the present research is to study possible risk factors, frequent genotypes of HCV and its association with different age groups. METHODS: Suspected blood samples from HCV patients were collected from different hospitals of Lahore, Pakistan. Out of 1000 HCV suspected samples, 920 samples were found HCV positive detected by Anti-HCV ELISA, CobasR. kit. The quantification of HCV load was determined by HCV quantification kit and LINEAR ARRAY KIT (Roche) was used for genotype determination by Real-Time PCR (ABI). Statistical analysis was done by using Microsoft Excel. RESULTS: Out of 920 subjects, 77 subjects (8.4%) were false positive and they were not detected by nested PCR. Three PCR positive samples were untypeable. Genotype 3 was predominant in Lahore which was 83.5%, whereas type 1 and 2 were 5.1% and 0.7% respectively. There were also mixed genotypes detected, 1 and 3 were 0.4%, 2 and 3 were 1.41% and 3 and 4 were 0.2% only. Male were more infected of HCV in the age <40 years and females >40years. CONCLUSION: The major risk factor for HCV transmission is by use of unsterilized razors/blades. It is necessary to spread awareness among the general population of Pakistan about HCV transmission risk factors. Regular physical examination at least once a year is recommended, so that early detection of HCV could be done.

Superhydrophobicity, UV protection and oil/water separation properties of fly ash/Trimethoxy(octadecyl)silane coated cotton fabrics.

The presented study proposed simple and low-cost approach for improvement in UV protection and superhydrophobic properties of cotton fabrics by coating of mechanically activated fly ash particles. The maximum UV blocking was observed for 3 wt% fly ash, where UV transmittance decreased from 14.19% of untreated fabric to 0.11% of coated fabric. After subsequent treatment of Trimethoxy(octadecyl)silane (OTMS) on fly ash coated fabrics, the water contact angle was increased to 143°, 147° and 153° for fly ash concentration of 1, 2 and 3 wt% respectively. From Cassie-Baxter theories, the unwetted fraction of air pockets were estimated to be 43%, 55% and 67% respectively for 1, 2 and 3 wt% of fly ash particles. Furthermore, the coated fabrics showed great potentials for separation of floating oil layer, underwater oil droplet or oil/water mixture. The separation efficiency of 98%, 96%, 97% and 95% was obtained for selected model oils toluene, n-hexane, chloroform and petro ether, respectively.

Corrigendum to 'Intravitreal ranibizumab for treatment of choroidal neovascularization secondary to a bilateral choroidal osteoma' [Am. J. Ophthalmol. Case Reports (4) (2016) 7-10].

[This corrects the article DOI: 10.1016/j.ajoc.2016.06.009.].

A review of scleral buckle procedures performed at a tertiary care center in Karachi, Pakistan.

This retrospective study was done to evaluate the visual and anatomic outcomes of scleral buckling for the repair of rhegmatogenous retinal detachment (RRD). All scleral buckle procedures performed at the Aga Khan University Hospital, Karachi, from May 1999 to April 2012 were included. A total of 75 eyes of 72 patients were studied. The mean age of patients at surgery was 33.0±17.2 years. The mean logarithm of the minimum angle of resolution (logMAR) visual acuity (VA) was 0.9±0.8 pre-operatively and 0.5±0.6 at 1 year (p=0.018). At baseline, 27(36%) eyes had a best corrected visual acuity (BCVA) of 20/50 or better, while at 1 year after surgery 47(63.5%) eyes had BCVA of 20/50 or better. Retina had successfully attached after first attempt in 70(93.3%) cases. Scleral buckling for the repair of RRD resulted in a high anatomical success rate as well as significant improvement in visual acuity.

Intravitreal ranibizumab for treatment of choroidal neovascularization secondary to a bilateral choroidal osteoma.

PURPOSE: Choroidal osteomas are benign intraocular tumors that classically present in females. Despite their benign nature, significant visual acuity loss can occur due to retinal pigment epithelium degeneration. We report an unusual case of bilateral choroidal osteoma in a young boy. OBSERVATION: A 16 year old boy presented to the Aga Khan University Hospital with a history of painless, bilateral deteriorating vision over past few months. Examination showed best corrected visual acuity as 20/200 in the right eye and 20/400 in the left eye. Funduscopy revealed a well-defined lesion in the juxtafoveal region of both eyes. A diagnosis of (bilateral) choroidal osteoma was subsequently made on the basis of optical coherence tomography, fundus fluorescein angiography, Indocyanine green and B-scan ultrasonography. The presence of choroidal neovascularization with sub retinal fluid was also established on OCT. The patient was treated with three intravitreal Ranizumab injections. At the follow up visit, vision had improved to 20/50 in the right eye and 20/200 in the left. Sub retinal fluid had also resolved. CONCLUSIONS: and importance: Intravitreal Ranizumab may be an effective alternative in the management of choroidal neovascularization secondary to choroidal osteoma.

Removal of silicone oil: prognostic factors and incidence of retinal redetachment.

PURPOSE: To evaluate the incidence of retinal redetachment after the removal of silicone oil endotamponade for complicated retinal detachment and identify possible factors affecting outcome. METHODS: This is a retrospective review of 173 patients who underwent pars plana vitrectomy with silicone oil tamponade for complex retinal detachment and subsequent removal of silicone oil (ROSO). The outcome factors studied included anatomical success, best-corrected visual acuity and intraocular pressure pre- and post-ROSO. RESULTS: Anatomical success was achieved in 167 of the 173 eyes (96.5%) after ROSO. The mean duration of silicone oil tamponade was 70 ± 48 weeks (median, 56 weeks; mode, 48 weeks). The cause for primary retinal detachment was proliferative diabetic retinopathy in 36 (20.8%) and proliferative vitreoretinopathy in 137 of 173 cases (79.2%). Best-corrected visual acuity of greater than 20/100 was achieved in 83 cases (49.4%) at 3 months after ROSO. Levene's test for equality of variances was used to determine the association between previous unsuccessful retinal surgeries and redetachment (P = 0.523) and between duration of endotamponade and anatomical success (P = 0.451). CONCLUSION: The incidence of retinal redetachment after ROSO in our study was 3.46%. Aggressive removal of the vitreous base, performing retinotomies, ensuring complete silicone oil filling for adequate tamponade, and argon retinopexy can lead to low complication rates and improved outcomes.