In Situ Generation of Cellulose Nanocrystals in Polycaprolactone Nanofibers: Effects on Crystallinity, Mechanical Strength, Biocompatibility, and Biomimetic Mineralization

Joshi, Mahesh Kumar,Tiwari, Arjun Prasad,Pant, Hem Raj,Shrestha, Bishnu Kumar,Kim, Han Joo,Park, Chan Hee,Kim, Cheol Sang American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.35

<P>Post-electrospinning treatment is a facile process to improve the properties of electrospun nanofibers for various applications. This technique is commonly used when direct electrospinning is not a suitable option to fabricate a nonwoven membrane of the desired polymer in a preferred morphology. In this study, a representative natural-synthetic hybrid of cellulose acetate (CA) and polycaprolactone (PCL) in different ratios was fabricated using an electrospinning process, and CA in the hybrid fiber was transformed into cellulose (CL) by post-electrospinning treatment via alkaline saponification. Scanning electron microscopy was employed to study the effects of polymer composition and subsequent saponification on the morphology of the nanofibers. Increasing the PCL content in the PCL/CA blend solution caused a gradual decrease in viscosity, resulting in smoother and more uniform fibers. The saponification of fibers lead to pronounced changes in the physicochemical properties. The crystallinity of the PCL in the composite fiber was varied according to the composition of the component polymers. The water contact angle was considerably decreased (from 124° to less than 20°), and the mechanical properties were greatly enhanced (Young’s Modulus was improved by ≈20–30 fold, tensile strength by 3–4 fold, and tensile stress by ≈2–4 fold) compared to those of PCL and PCL/CA membranes. Regeneration of cellulose chains in the nanofibers increased the number of hydroxyl groups, which increased the hydrogen bonding, thereby improving the mechanical properties and wettability of the composite nanofibers. The improved wettability and presence of surface functional groups enhanced the ability to nucleate bioactive calcium phosphate crystals throughout the matrix when exposed to a simulated body fluid solution. Experimental results of cell viability assay, confocal microscopy, and scanning electron microscopy imaging showed that the fabricated nanofibrous membranes have excellent ability for MC3T3-E1 cell proliferation and growth. Given the versatility and widespread use of cellulose–synthetic hybrid systems in the construction of tissue-engineered scaffolds, this work provides a novel strategy to fabricate the biopolymer-based materials for applications in tissue engineering and regenerative medicine.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-35/acsami.5b04682/production/images/medium/am-2015-04682d_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b04682'>ACS Electronic Supporting Info</A></P>

Multi-layered macroporous three-dimensional nanofibrous scaffold via a novel gas foaming technique

Joshi, Mahesh Kumar,Pant, Hem Raj,Tiwari, Arjun Prasad,kim, Han Joo,Park, Chan Hee,Kim, Cheol Sang Elsevier 2015 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.275 No.-

<P><B>Abstract</B></P> <P>In the past decade, considerable efforts have been made to fabricate the biomimetic scaffolds from electrospun nanofibers for tissue engineering applications. However, one of the major concerns with electrospun nanofibrous scaffolds is the densely packed fibers in two-dimensional (2-D) array which impedes their applicability in tissue regeneration. To overcome this problem, a simple and facile post-electrospinning procedure was developed to modify a densely packed 2-D electrospun membrane into low density three-dimensional (3-D) scaffolds. In this strategy, an electrospun nanofibrous mat was immersed in a sodium borohydride (SB) solution. The interconnected pores of a mat are filled with the SB solution driven by capillary forces where it undergoes hydrolysis to produce hydrogen gas. The <I>in situ</I> generated gas molecules form clusters to minimize the free energy resulting in pore nucleation that reorganizes the nanofibers to form a low density, macroporous, spongy and multi-layered 3-D scaffold. Electrospun mats of various polar and non-polar polymers were subjected to post-electrospinning process to monitor the fabrication process. It has been found that the solvent for sodium borohydride (either water or methanol) played a crucial role in post-electrospinning process. Only the electrospun mat of polar polymers were amended into 3-D architecture using aqueous SB solution while methanol solution was found equally effective for both polar and non-polar polymers. Moreover, the fabrication process was fast in methanol solution compared to an aqueous solution due to the rapid liberation of hydrogen gas from the methanolysis reaction compared to the hydrolysis reaction. This process will reveal a new approach for the fabrication of a three-dimensional, low-density, nanofibrous materials for biomedical and industrial applications using a wide variety of polymers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Gas foaming technique is applied to prepare a 3-D nanofibrous scaffold. </LI> <LI> Sodium borohydride solution is introduced as gas foaming reagent. </LI> <LI> Novel mechanism for <I>in situ</I> gas foaming is demonstrated. </LI> <LI> Nature of the polymers affects the fabrication process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile Synthesis of Magnetically Separable Silver based Nanocomposite for Waste Water Treatment

Mahesh Kumar Joshi,Cheol Sang Kim,Hem Raj Pant,Sung Won Ko,Han Joo Kim,Jeong In Kim,Chan Hee Park 한국정밀공학회 2014 한국정밀공학회 학술발표대회 논문집 Vol.2014 No.5월

Experimental Realization of Matrix Converter Based Induction Motor Drive under Various Abnormal Voltage Conditions

Vinod Kumar,Ramesh Chand Bansal,Raghuveer Raj Joshi 대한전기학회 2008 International Journal of Control, Automation, and Vol.6 No.5

While the matrix converter has many advantages that include bi-directional power flow, a size reduction, a long lifetime, and sinusoidal input currents, it is vulnerable to the input voltage disturbances, because it directly exchanges the input voltage to the output voltage. So, in this paper, a critical evaluation of the effect of various abnormal voltage conditions like unbalanced power supply, balanced non-sinusoidal power supply, input voltage sags and short time blackout of power supply on matrix converter fed induction motor drives is presented. The operation under various abnormal conditions has been analyzed. For this, a 230V, 250VA three phase to three phase matrix converter (Me) fed induction motor drive prototype is implemented using DSP based controller and tests have been carried out to evaluate and improve the stability of system under typical abnormal conditions. Digital storage oscilloscope & power quality analyzer are used for experimental observations.

Study of the Changes in Composition of Ammonium Diuranate with Progress of Precipitation, and Study of the Properties of Ammonium Diuranate and its Subsequent Products Produced from both Uranyl Nitrate and Uranyl Fluoride Solutions

Subhankar Manna,Raj Kumar,Santosh K. Satpati,Saswati B. Roy,Jyeshtharaj B. Joshi 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.3

Uranium metal used for fabrication of fuel for research reactors in India is generally produced by magnesio-thermic reduction of UF4. Performance of magnesio-thermic reaction and recovery and quality of uranium largely depends on properties of UF4. As ammonium diuranate (ADU) is first product in powder form in the process flow-sheet, properties of UF4 depend on properties of ADU. ADU is generally produced from uranyl nitrate solution (UNS) for natural uranium metal production and from uranyl fluoride solution (UFS) for low enriched uranium metal production. In present paper, ADU has been produced via both the routes. Variation of uranium recovery and crystal structure and composition of ADU with progress in precipitation reaction has been studied with special attention on first appearance of the precipitate Further, ADU produced by two routes have been calcined to UO3, then reduced to UO2 and hydroflorinated to UF4. Effect of two different process routes of ADU precipitation on the characteristics of ADU, UO3, UO2 and UF4 were studied here.

Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis) Ciferri

Satyabrata Nanda,Subodh Kumar Chand,Purander Mandal,Pradyumna Tripathy,Raj Kumar Joshi 한국식물병리학회 2016 Plant Pathology Journal Vol.32 No.6

Purple blotch, caused by Alternaria porri (Ellis)Cifferi, is a serious disease incurring heavy yield lossesin the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification ofeffective resistance sources for use in host resistancebreeding. A total of 43 Allium genotypes were screenedfor purple blotch resistance under field conditions. Allium cepa accession ‘CBT-Ac77’ and cultivar ‘ArkaKalyan’ were observed to be highly resistant. In vitroinoculation of a selected set of genotypes with A. porri,revealed that 7 days after inoculation was suitableto observe the disease severity. In vitro screening of43 genotypes for resistance to A. porri revealed tworesistant lines. An additional 14 genotypes showedconsistent moderate resistance in the field as well as invitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least diseaseindex and can be used for interspecific hybridizationwith cultivated onion. Differential reaction analysis ofthree A. porri isolates (Apo-Chiplima, Apn-Nasik, Apg-Guntur) in 43 genotypes revealed significant variationamong the evaluated Allium species (P = 0.001). Alltogether, the present study suggest that, the newlyidentified resistance sources can be used as potentialdonors for ongoing purple blotch resistance breedingprogram in India.

Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis) Ciferri

Nanda, Satyabrata,Chand, Subodh Kumar,Mandal, Purander,Tripathy, Pradyumna,Joshi, Raj Kumar The Korean Society of Plant Pathology 2016 Plant Pathology Journal Vol.32 No.6

Purple blotch, caused by Alternaria porri (Ellis) Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession 'CBT-Ac77' and cultivar 'Arka Kalyan' were observed to be highly resistant. In vitro inoculation of a selected set of genotypes with A. porri, revealed that 7 days after inoculation was suitable to observe the disease severity. In vitro screening of 43 genotypes for resistance to A. porri revealed two resistant lines. An additional 14 genotypes showed consistent moderate resistance in the field as well as in vitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least disease index and can be used for interspecific hybridization with cultivated onion. Differential reaction analysis of three A. porri isolates (Apo-Chiplima, Apn-Nasik, Apg-Guntur) in 43 genotypes revealed significant variation among the evaluated Allium species (P = 0.001). All together, the present study suggest that, the newly identified resistance sources can be used as potential donors for ongoing purple blotch resistance breeding program in India.

Ex-situ conservation and cytotoxic activity assessment of native medicinal orchid: Coelogyne stricta

Thapa, Bir Bahadur,Thakuri, Laxmi Sen,Joshi, Pusp Raj,Chand, Krishna,Rajbahak, Sabari,Sah, Anil Kumar,Shrestha, Resha,Paudel, Mukti Ram,Park, So Young,Pant, Bijaya The Korean Society of Plant Biotechnology 2020 JOURNAL OF PLANT BIOTECHNOLOGY Vol.47 No.4

Ex-situ conservation of the ornamental and medicinal orchid, Coelogyne stricta, was performed by mass propagation using seed culture. Propagation stages were optimized using full- and half-strength solidified MS medium with different phytohormones. Maximum seed germination (88 ± 0.5% over 6 weeks of culture) was achieved on half-strength MS medium supplemented with 15% coconut water. Maximum shoot numbers were found on full-strength MS medium supplemented with 1 mg/L BAP, 2 mg/L Kinetin, and 10% coconut water, while the longest root was developed on full-strength MS medium with 1.5 mg/L IBA. A 2:1:1 combination of coco-peat, pine bark, and sphagnum moss was found to be a suitable potting mixture resulting in 80% seedling survivability. The cytotoxic activity of extracts of both wild plants and in vitro-developed protocorms was determined using an MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay on a cervical cancer cell line. The wild plant extract inhibited the growth of 41.99% of cells, showing that this extract has moderate cytotoxic activity toward cervical cancer cells.

Genome Wide Analysis of the Potato Soft Rot Pathogen Pectobacterium carotovorum Strain ICMP 5702 to Predict Novel Insights into Its Genetic Features

Tista Mallick,Rukmini Mishra,Sasmita Mohanty,Raj Kumar Joshi 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.2

Pectobacterium carotovorum subsp. carotovorum (Pcc) is a gram-negative, broad host range bacterial pathogen which causes soft rot disease in potatoes as well as other vegetables worldwide. While Pectobacterium infection relies on the production of major cell wall degrading enzymes, other virulence factors and the mechanism of genetic adaptation of this pathogen is not yet clear. In the present study, we have performed an in-depth genome-wide characterization of Pcc strain ICMP5702 isolated from potato and compared it with other pathogenic bacteria from the Pectobacterium genus to identify key virulent determinants. The draft genome of Pcc ICMP5702 contains 4,774,457 bp with a G + C content of 51.90% and 4,520 open reading frames. Genome annotation revealed prominent genes encoding key virulence factors such as plant cell wall degrading enzymes, flagella-based motility, phage proteins, cell membrane structures, and secretion systems. Whereas, a majority of determinants were conserved among the Pectobacterium strains, few notable genes encoding AvrE-family type III secretion system effectors, pectate lyase and metalloprotease in addition to the CRISPR-Cas based adaptive immune system were uniquely represented. Overall, the information generated through this study will contribute to decipher the mechanism of infection and adaptive immunity in Pcc.