Use of an intelligent tutoring system for a curriculum on augmentative and alternative communication: Feasibility for implementation.

BACKGROUND: Over 8 million children with disabilities live in Africa and are candidates for augmentative and alternative communication (AAC), yet formal training for team members, such as speech-language therapists and special education teachers, is extremely limited. Only one university on the continent provides postgraduate degrees in AAC, and other institutions provide only short modules at an undergraduate level. The need for an introductory training course on AAC that is accessible by university students continent-wide was identified. An online programme, namely an intelligent tutoring system (ITS), was identified as a possible option to facilitate interactive learning without the need for synchronous teaching. The use of an ITS is shown to be effective in developing knowledge and clinical reasoning in the health and rehabilitation fields. However, it has not yet been applied to student teaching in the field of AAC. AIM: To determine both the feasibility of an ITS to implement an AAC curriculum for students in four African countries, and the usability and effectiveness of such a system as a mechanism for learning about AAC. METHOD & PROCEDURES: The study included two components: the development of a valid AAC curriculum; and using the ITS to test the effectiveness of implementation in a pre- and post-test design with 98 speech-language therapy and special education students from five universities. OUTCOMES & RESULTS: Statistically significant differences were obtained between pre- and post-test assessments. Students perceived the learning experience as practical, with rich content. CONCLUSIONS & IMPLICATIONS: The findings suggest that the ITS-based AAC curriculum was positively perceived by the students and potentially offers an effective means of providing supplementary AAC training to students, although modifications to the system are still required. WHAT THIS PAPER ADDS: What is already known on the subject Professionals typically lack formal training in AAC. In Africa, this presents a serious challenge as there are over 8 million children who are candidates for AAC. A need for an introductory training course on AAC, which can be accessed by university students continent-wide, was identified. What this paper adds to existing knowledge An AAC curriculum was developed and integrated into an ITS, an online programme allowing interactive learning through asynchronous teaching. Students from four African countries completed the AAC ITS curriculum. The curriculum was positively received by the students and statistically significant changes in knowledge were identified. What are the practical and clinical implications of this work? This feasibility study shows that the use of an ITS is an effective means of providing AAC training to university students in these African countries. The results provide a valuable contribution toward ensuring the equitable distribution of AAC training opportunities in the African context. This will have a significant positive impact on those who are candidates for AAC.

Genome-resolved carbon processing potential of tropical peat microbiomes from an oil palm plantation.

Tropical peatlands in South-East Asia are some of the most carbon-dense ecosystems in the world. Extensive repurposing of such peatlands for forestry and agriculture has resulted in substantial microbially-driven carbon emissions. However, we lack an understanding of the microorganisms and their metabolic pathways involved in carbon turnover. Here, we address this gap by reconstructing 764 sub-species-level genomes from peat microbiomes sampled from an oil palm plantation located on a peatland in Indonesia. The 764 genomes cluster into 333 microbial species (245 bacterial and 88 archaeal), of which, 47 are near-complete (completeness ≥90%, redundancy ≤5%, number of unique tRNAs ≥18) and 170 are substantially complete (completeness ≥70%, redundancy ≤10%). The capacity to respire amino acids, fatty acids, and polysaccharides was widespread in both bacterial and archaeal genomes. In contrast, the ability to sequester carbon was detected only in a few bacterial genomes. We expect our collection of reference genomes to help fill some of the existing knowledge gaps about microbial diversity and carbon metabolism in tropical peatlands.

Visual saliency detection approach for long-term ECG analysis.

BACKGROUND AND OBJECTIVE: Detection and analysis of QRS-complex as well as the processing of electrocardiogram (ECG) signal using computers are being practiced for over the last fifty-eight years, approximately, and yet the thirst of designing superior ECG processing and recognition algorithms still captures researchers' attention around the globe. A saliency detection-based technique for the processing of one-dimensional biomedical signals such as ECG is proposed here for the first time, to the best or our knowledge. METHODS AND RESULTS: In this proposed research work, first, a trigonometric threshold-based technique is used to identify the QRS-complexes from the ECG signal. Motion-artifact (MA) and sudden-change-in-baseline (SCB) types of noises are considered to be the toughest among others to filter out from the ECG signals as the bandwidths of these two types of noises overlap with that of the ECG. Only one feature is extracted from each of the QRS-complex-intervals, and the normalised values of this feature are arranged in the form of a gray-scale image. Then, a saliency detection-based technique is applied iteratively on the gray-scale image to detect those regions of the ECG signals, which are highly corrupted with MA and (or) SCB noises. Next, three unique geometric-features are extracted from the rest of the QRS-complexes, which are not corrupted with MA or SCB noises, and the normalised values of these three features are arranged in the form of an Red-Green-Blue (RGB) image. Again, the saliency detection-based technique is applied to identify the abnormal QRS-complexes from the RGB image. CONCLUSIONS: The technique is tested on long-term ECG signals; totaling a duration of 17.54 days, and its performance is evaluated through both quantitative and qualitative measures. The applicability, scope of implement in real-time scenarios, advantage of the proposed technique over the existing ones are discussed with a group of clinicians and cardiologists, and very affirmative and encouraging responses are received from them.

A Singular Spectrum Analysis-Based Data-Driven Technique for the Removal of Cardiogenic Oscillations in Esophageal Pressure Signals.

Objective: Assessing the respiratory and lung mechanics of the patients in intensive care units is of utmost need in order to guide the management of ventilation support. The esophageal pressure ([Formula: see text]) signal is a minimally invasive measure, which portrays the mechanics of the lung and the pattern of breathing. Because of the close proximity of the lung to the beating heart inside the thoracic cavity, the [Formula: see text] signals always get contaminated with that of the oscillatory-pressure-signal of the heart, which is known as the cardiogenic oscillation ([Formula: see text]) signal. However, the area of research addressing the removal of [Formula: see text] from [Formula: see text] signal is still lagging behind. Methods and results: This paper presents a singular spectrum analysis-based high-efficient, adaptive and robust technique for the removal of [Formula: see text] from [Formula: see text] signal utilizing the inherent periodicity and morphological property of the [Formula: see text] signal. The performance of the proposed technique is tested on [Formula: see text] signals collected from the patients admitted to the intensive care unit, cadavers, and also on synthetic [Formula: see text] signals. The efficiency of the proposed technique in removing [Formula: see text] from the [Formula: see text] signal is quantified through both qualitative and quantitative measures, and the mean opinion scores of the denoised [Formula: see text] signal fall under the categories 'very good' as per the subjective measure. Conclusion and clinical impact: The proposed technique: (1) does not follow any predefined mathematical model and hence, it is data-driven, (2) is adaptive to the sampling rate, and (3) can be adapted for denoising other biomedical signals which exhibit periodic or quasi-periodic nature.

A singular spectrum analysis-based model-free electrocardiogram denoising technique.

BACKGROUND AND OBJECTIVE: An efficient and robust electrocardiogram (ECG) denoising technique caters three-fold benefits in the subsequent processing steps: first, it helps improving the accuracy of extracted features. Second, the improved accuracy in the extracted features enhances the performance as well as the reliability of computerised cardiovascular-disease diagnosis systems, and third, it also makes the interpretation task easier for the clinicians. Albeit a number of ECG denoising techniques are proposed in the literature, but most of these techniques suffer from one or more of the following drawbacks: i) model or function dependency, ii) sampling-rate dependency, or iii) high time-complexity. METHODS: This paper presents a singular spectrum analysis (SSA)-based ECG denoising technique addressing most of these afore-mentioned shortcomings. First, a trajectory matrix of dimension K × L is formed using the original one-dimensional ECG signal of length N. In SSA operation the parameter L, which is denoted as the window-length, plays a very important role and is related to the sampling frequency of the signal. In this research the value of L is calculated dynamically based on the morphological property of the ECG signal. Then, the matrix is decomposed using singular value decomposition technique, and the principal components (PC) of the original ECG signal are computed. Next, the reconstructed components (RC) are calculated from the PCs, and all the RCs are filtered through Butterworth bandpass and notch filters. An optimum number of filtered RCs are retained based on their significance. Finally, these retained RCs are summed up to obtain the denoised ECG signal. RESULTS: Evaluation result shows that the proposed technique outperforms state-of-the-art ECG denoising methods; in particular, the mean opinion score of the denoised signal falls under the category 'very good' as per the gold standard subjective measure. CONCLUSIONS: Both the quantitative and qualitative distortion measure metrics show that the proposed ECG denoising technique is robust enough to filter various noises present in the signal without jeopardizing the clinical content. The proposed technique could be adapted for denoising other biomedical signals exhibiting periodic or quasi-periodic nature such as photoplethysmogram and esophageal pressure signal.

Evaluation of Cyclosaplin Efficacy Using a Silk Based 3D Tumor Model.

Development of novel anti-cancer peptides requires a rapid screening process which can be accelerated by using appropriate in vitro tumor models. Breast carcinoma tissue is a three-dimensional (3D) microenvironment, which contains a hypoxic center surrounded by dense proliferative tissue. Biochemical clues provided by such a 3D cell mass cannot be recapitulated in conventional 2D culture systems. In this experiment, we evaluate the efficacy of the sandalwood peptide, cyclosaplin, on an established in vitro 3D silk breast cancer model using the invasive MDA-MB-231 cell line. The anti-proliferative effect of the peptide on the 3D silk tumor model is monitored by alamarBlue assay, with conventional 2D culture as control. The proliferation rate, glucose consumed, lactate dehydrogenase (LDH), and matrix metalloproteinase 9 (MMP-9) activity of human breast cancer cells are higher in 3D constructs compared to 2D. A higher concentration of drug is required to achieve 50% cell death in 3D culture than in 2D culture. The cyclosaplin treated MDA-MB-231 cells showed a significant decrease in MMP-9 activity in 3D constructs. Microscopic analysis revealed the formation of cell clusters evenly distributed in the scaffolds. The drug treated cells were less in number, smaller and showed unusual morphology. Overall, these findings indicate the role of cyclosaplin as a promising anti-cancer therapeutic.

Compression of Steganographed PPG Signal with Guaranteed Reconstruction Quality Based on Optimum Truncation of Singular Values and ASCII Character Encoding.

OBJECTIVE: Extraction and analysis of various clinically significant features of photoplethysmogram (PPG) signals for monitoring several physiological parameters as well as for biometric authentication have become important areas of research in recent years. However, PPG signal compression; particularly quality-guaranteed compression, and steganography of patient's secret information is still lagging behind. METHOD: This paper presents a robust, reliable and highly-efficient singular value decomposition (SVD) and lossless ASCII character encoding (LL-ACE)-based quality-guaranteed PPG compression algorithm. This algorithm can not only be used to compress PPG signals but also do so for steganographed PPG signals that include the patient information. RESULT AND CONCLUSION: It is worth mentioning that such an algorithm is being proposed for the first time to compress steganographed PPG signals. The algorithm is tested on PPG signals collected from four different databases, and its performance is assessed using both quantitative and qualitative measures. The proposed steganographed PPG compression algorithm provides a compression ratio that is much higher than that provided by other algorithms that are designed to compress the PPG signals only. SIGNIFICANCE: (1) the clinical quality of the reconstructed PPG signal can be controlled precisely, (2) the patient's personal information is restored with no errors, (3) high compression ratio, and (4) the PPG signal reconstruction error is neither dependent on the steganographic operation nor on the size of the patient information data.

In vivo mimicking model for solid tumor towards hydromechanics of tissue deformation and creation of necrosis.

The present work addresses transvascular and interstitial fluid transport inside a solid tumor surrounded by normal tissue (close to an in vivo mimicking setup). In general, biological tissues behave like a soft porous material and show mechanical behavior towards the fluid motion through the interstitial space. In general, forces like viscous drag that are associated with the fluid flow may compress the tissue material. On the macroscopic level, we try to model the motion of fluids and macromolecules through the interstitial space of solid tumor and the normal tissue layer. The transvascular fluid transport is assumed to be governed by modified Starling's law. The poroelastohydrodynamics (interstitial hydrodynamics and the deformation of tissue material) inside the tumor and normal tissue regions is modeled using linearized biphasic mixture theory. Correspondingly, the velocity distribution of fluid is coupled to the displacement field of the solid phase (mainly cellular phase and extracellular matrix) in both the normal and tumor tissue regions. The corresponding velocity field is used within the transport reaction equation for fluids and macromolecules through interstitial space to get the overall solute (e.g., nutrients, drug, and other macromolecules) distribution. This study justifies that the presence of the normal tissue layer plays a significant role in delaying/assisting necrosis inside the tumor tissue. It is observed that the exchange process of fluids and macromolecules across the interface of the tumor and normal tissue affects the effectiveness factor corresponding to the tumor tissue.

Sphingobactan, a new α-mannan exopolysaccharide from Arctic Sphingobacterium sp. IITKGP-BTPF3 capable of biological response modification.

An exopolysaccharide, from a new Arctic permafrost isolate, Sphingobacterium sp. IITKGP-BTPF3 was purified and characterized. Upon optimization of various parameters (pH, temperature, carbon and nitrogen source), the yield of EPS obtained was 1.42 g/L. Structural investigation through FT-IR, GC-MS/MS, HPLC and NMR (1D and 2D) revealed the molecule to be a mannan with α-(1 → 2) and α-(1 → 6) linkages. Anti-oxidant and macrophage immunomodulatory assays were employed for the assessment of bioactivity. Sphingobactan was found to be capable of scavenging superoxide anions, and reducing the nitric oxide production in LPS elicited murine macrophage (RAW 264.7) cell line. The in vitro findings indicate the potential of Sphingobactan as a biological response modification (BRM) agent, for containment and possible resolution of inflammatory response in vivo.

SVD and ASCII Character Encoding-Based Compression of Multiple Biosignals for Remote Healthcare Systems.

Advancements in electronics and miniaturized device fabrication technologies have enabled simultaneous acquisition of multiple biosignals (MBioSigs), but the area of compression of MBioSigs remains unexplored to date. This paper presents a robust singular value decomposition (SVD) and American standard code for information interchange (ASCII) character encoding-based algorithm for compression of MBioSigs for the first time to the best of our knowledge. At the preprocessing stage, MBioSigs are denoised, down sampled and then transformed to a two-dimensional (2-D) data array. SVD of the 2-D array is carried out and the dimensionality of the singular values is reduced. The resulting matrix is then compressed by a lossless ASCII character encoding-based technique. The proposed compression algorithm can be used in a variety of modes such as lossless, with or without using the down sampling operation. The compressed file is then uploaded to a hypertext preprocessor (PHP)-based website for remote monitoring application. Evaluation results show that the proposed algorithm provides a good compression performance; in particular, the mean opinion score of the reconstructed signal falls under the category "very good" as per the gold standard subjective measure.

Silk fibroin-Thelebolan matrix: A promising chemopreventive scaffold for soft tissue cancer.

Research of improved functional bio-mimetic matrix for regenerative medicine is currently one of the rapidly growing fields in tissue engineering and medical sciences. This study reports a novel bio-polymeric matrix, which is fabricated using silk protein fibroin from Bombyx mori silkworm and fungal exopolysaccharide Thelebolan from Antarctic fungus Thelebolus sp. IITKGP-BT12 by solvent evaporation and freeze drying method. Natural cross linker genipin is used to imprison the Thelebolan within the fibroin network. Different cross-linked and non-cross-linked fibroin/Thelebolan matrices are fabricated and biophysically characterized. Cross-linked thin films show robustness, good mechanical strength and high temperature stability in comparison to non-cross-linked and pure matrices. The 3D sponge matrices demonstrate good cytocompatibility. Interestingly, sustained release of the Thelebolan from the cross-linked matrices induce apoptosis in colon cancer cell line (HT-29) in time dependent manner while it is nontoxic to the normal fibroblast cells (L929).The findings indicate that the cross-linked fibroin/Thelebolan matrices can be used as potential topical chemopreventive scaffold for preclusion of soft tissue carcinoma.

A Mutual Authentication Framework for Wireless Medical Sensor Networks.

Wireless medical sensor networks (WMSN) comprise of distributed sensors, which can sense human physiological signs and monitor the health condition of the patient. It is observed that providing privacy to the patient's data is an important issue and can be challenging. The information passing is done via the public channel in WMSN. Thus, the patient, sensitive information can be obtained by eavesdropping or by unauthorized use of handheld devices which the health professionals use in monitoring the patient. Therefore, there is an essential need of restricting the unauthorized access to the patient's medical information. Hence, the efficient authentication scheme for the healthcare applications is needed to preserve the privacy of the patients' vital signs. To ensure secure and authorized communication in WMSN, we design a symmetric key based authentication protocol for WMSN environment. The proposed protocol uses only computationally efficient operations to achieve lightweight attribute. We analyze the security of the proposed protocol. We use a formal security proof algorithm to show the scheme security against known attacks. We also use the Automated Validation of Internet Security Protocols and Applications (AVISPA) simulator to show protocol secure against man-in-the-middle attack and replay attack. Additionally, we adopt an informal analysis to discuss the key attributes of the proposed scheme. From the formal proof of security, we can see that an attacker has a negligible probability of breaking the protocol security. AVISPA simulator also demonstrates the proposed scheme security against active attacks, namely, man-in-the-middle attack and replay attack. Additionally, through the comparison of computational efficiency and security attributes with several recent results, proposed scheme seems to be battered.

A p-Hydroxyphenacyl-Benzothiazole-Chlorambucil Conjugate as a Real-Time-Monitoring Drug-Delivery System Assisted by Excited-State Intramolecular Proton Transfer.

Among the well-known phototriggers, the p-hydroxyphenacyl (pHP) group has consistently enabled the very fast, efficient, and high-conversion release of active molecules. Despite this unique behavior, the pHP group has been ignored as a delivery agent, particularly in the area of theranostics, because of two major limitations: Its excitation wavelength is below 400 nm, and it is nonfluorescent. We have overcome these limitations by incorporating a 2-(2'-hydroxyphenyl)benzothiazole (HBT) appendage capable of rapid excited-state intramolecular proton transfer (ESIPT). The ESIPT effect also provided two unique advantages: It assisted the deprotonation of the pHP group for faster release, and it was accompanied by a distinct fluorescence color change upon photorelease. In vitro studies showed that the p-hydroxyphenacyl-benzothiazole-chlorambucil conjugate presents excellent properties, such as real-time monitoring, photoregulated drug delivery, and biocompatibility.

Fluorene-morpholine-based organic nanoparticles: lysosome-targeted pH-triggered two-photon photodynamic therapy with fluorescence switch on-off.

Nanocarrier-mediated photodynamic therapy (PDT) is an effective tool for anti-tumour treatment due to the targeted and image-guided delivery of photosensitizers (PSs) to diseased tissues. These nanocarriers range from inorganic, ceramic, polymeric to biological nanoparticles (NPs). Such PS-grafted bicomponent nanocarriers have limitations like (i) difficulty in surface modification, (ii) lower loading percentages of the therapeutic agent, (iii) unstable physical encapsulation, etc. By any means, if we can prepare PSs directly as NPs then we can surpass the above drawbacks. Hence, we synthesised new two-photon fluorene-functionalised morpholine (Fluo-Mor)-based organic NPs that showed strong fluorescence and profound photodynamic therapy (PDT) activity only in acidic medium. Such a pH-responsive appearance of fluorescence enables Fluo-Mor NPs for the real time monitoring of photodynamic therapeutic activity selectively in low-pH organelles viz. lysosome. Cytotoxicity of Fluo-Mor NPs was monitored using time-dependent and dose-dependent cancer cell viability assay and confocal imaging.

Coumarin-benzothiazole-chlorambucil (Cou-Benz-Cbl) conjugate: an ESIPT based pH sensitive photoresponsive drug delivery system.

We have developed an ESIPT based drug delivery system (DDS), Cou-Benz-Cbl conjugate, by incorporating a benzothiazole group at the 8th position of the 7-hydroxy-coumarin moiety for pH sensitive fluorescence properties and photocontrolled release of the anticancer drug chlorambucil. The Cou-Benz-Cbl conjugate exhibited unique photophysical properties like good absorbance at around 350 nm, a large Stokes shift (∼151 nm) and pH sensitive fluorescence properties. The pH sensitive fluorescence properties of the Cou-Benz-Cbl conjugate can be ascribed to an ESIPT turn "on and off" mechanism. At physiological pH, the ESIPT gets turned "off" and a blue fluorescence of the coumarin moiety was observed, but at acidic pH, the ESIPT gets turned "on" and a green fluorescence was noted. Photolysis of the Cou-Benz-Cbl conjugate using UV light of wavelength ≥365 nm resulted in the efficient release of the anticancer drug chlorambucil. Cellular uptake studies revealed that the Cou-Benz-Cbl conjugate was easily internalized inside the cancer cells. Further, an MTT assay showed that the Cou-Benz-Cbl conjugate has a good biocompatibility and low cytotoxicity towards the MDA-MB-231 cell line, whereas upon exposure to UV light, the Cou-Benz-Cbl conjugate exhibited enhanced cytotoxicity compared to the free drug due to the effective release of the anticancer drug chlorambucil inside the cancer cell.

A secure and efficient chaotic map-based authenticated key agreement scheme for telecare medicine information systems.

Advancement in network technology provides new ways to utilize telecare medicine information systems (TMIS) for patient care. Although TMIS usually faces various attacks as the services are provided over the public network. Recently, Jiang et al. proposed a chaotic map-based remote user authentication scheme for TMIS. Their scheme has the merits of low cost and session key agreement using Chaos theory. It enhances the security of the system by resisting various attacks. In this paper, we analyze the security of Jiang et al.'s scheme and demonstrate that their scheme is vulnerable to denial of service attack. Moreover, we demonstrate flaws in password change phase of their scheme. Further, our aim is to propose a new chaos map-based anonymous user authentication scheme for TMIS to overcome the weaknesses of Jiang et al.'s scheme, while also retaining the original merits of their scheme. We also show that our scheme is secure against various known attacks including the attacks found in Jiang et al.'s scheme. The proposed scheme is comparable in terms of the communication and computational overheads with Jiang et al.'s scheme and other related existing schemes. Moreover, we demonstrate the validity of the proposed scheme through the BAN (Burrows, Abadi, and Needham) logic.

Cryptanalysis and improvement of Yan et al.'s biometric-based authentication scheme for telecare medicine information systems.

Remote user authentication is desirable for a Telecare Medicine Information System (TMIS) for the safety, security and integrity of transmitted data over the public channel. In 2013, Tan presented a biometric based remote user authentication scheme and claimed that his scheme is secure. Recently, Yan et al. demonstrated some drawbacks in Tan's scheme and proposed an improved scheme to erase the drawbacks of Tan's scheme. We analyze Yan et al.'s scheme and identify that their scheme is vulnerable to off-line password guessing attack, and does not protect anonymity. Moreover, in their scheme, login and password change phases are inefficient to identify the correctness of input where inefficiency in password change phase can cause denial of service attack. Further, we design an improved scheme for TMIS with the aim to eliminate the drawbacks of Yan et al.'s scheme.

1-Acetylpyrene-salicylic acid: photoresponsive fluorescent organic nanoparticles for the regulated release of a natural antimicrobial compound, salicylic acid.

Photoresponsive 1-acetylpyrene-salicylic acid (AcPy-SA) nanoparticles (NPs) were developed for the regulated release of a natural antimicrobial compound, salicylic acid. The strong fluorescent properties of AcPy-SA NPs have been extensively used for potential in vitro cell imaging. The phototrigger capability of our newly prepared AcPy-SA NPs was utilized for the efficient release of an antimicrobial compound, salicylic acid. The photoregulated drug release of AcPy-SA NPs has been shown by the subsequent switching off and on of a visible-light source. In vitro biological studies reveal that AcPy-SA NPs of ∼68 nm size deliver the antimicrobial drug salicylic acid into the bacteria cells (Pseudomonas aeruginosa) and efficiently kill the cells upon exposure to visible light (≥410 nm). Such photoresponsive fluorescent organic NPs will be highly beneficial for targeted and regulated antimicrobial drug release because of their biocompatible nature, efficient cellular uptake, and light-induced drug release ability.

Security enhancement of a biometric based authentication scheme for telecare medicine information systems with nonce.

Telecare medicine information systems (TMIS) present the platform to deliver clinical service door to door. The technological advances in mobile computing are enhancing the quality of healthcare and a user can access these services using its mobile device. However, user and Telecare system communicate via public channels in these online services which increase the security risk. Therefore, it is required to ensure that only authorized user is accessing the system and user is interacting with the correct system. The mutual authentication provides the way to achieve this. Although existing schemes are either vulnerable to attacks or they have higher computational cost while an scalable authentication scheme for mobile devices should be secure and efficient. Recently, Awasthi and Srivastava presented a biometric based authentication scheme for TMIS with nonce. Their scheme only requires the computation of the hash and XOR functions.pagebreak Thus, this scheme fits for TMIS. However, we observe that Awasthi and Srivastava's scheme does not achieve efficient password change phase. Moreover, their scheme does not resist off-line password guessing attack. Further, we propose an improvement of Awasthi and Srivastava's scheme with the aim to remove the drawbacks of their scheme.

Isolation and characterization of extracellular polysaccharide Thelebolan produced by a newly isolated psychrophilic Antarctic fungus Thelebolus.

The present investigation is on a newly isolated psychrophilic Antarctic filamentous Ascomycetous fungus that has been identified as Thelebolus sp. and given the designation of Thelebolus sp. IITKGP-BT12. The culture was primarily identified through morphological studies, and was further confirmed by 18S rRNA sequencing (GenBank Accession No. KC191572), which revealed its close relatedness with Thelebolus microsporus. The exopolysaccharide (EPS) produced (1.94 g L(-1)) by the fungus was isolated, purified and characterized as glucan having an average molecular mass of 5×10(5)Da. The structure of EPS was determined by gas chromatography with tandem mass spectrometry (GC-MS/MS), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) studies ((1)H, (13)C and HSQC). NMR analysis indicated the presence of (1→3)-linked ß-d-glucan backbone with (1→6)-linked branches of ß-d-glucopyranosyl units. Antiproliferative activity of EPS was demonstrated in B16-F0 cells, with IC50 of 275.42 µg m L(-1). Flow cytometry analysis and DNA fragmentation studies revealed that the cytotoxic action of the EPS mediated apoptosis in cancer cells. This is the first ever report on bioactive EPS thelebolan from Thelebolus sp.