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1.
Biofactors ; 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-32039535

RESUMO

Reprogrammed metabolism is key biochemical characteristic of malignant cells, which represents one of the emerging hallmarks of cancer. Currently, there is rising contemplation on oxidative pentose phosphate pathway (PPP) enzymes as potential therapeutic hits due to their affiliation with tumor metabolism. 6-Phosphogluconate dehydrogenase (6PGD), third oxidative decarboxylase of PPP, has received a great deal of attention during recent years due to its critical role in tumorigenesis and redox homeostasis. 6PGD has been reported to overexpress in number of cancer types and its hyperactivation is mediated through post-transcriptional and post-translational modifications by YTH domain family 2 (YTHDF2), Nrf2 (nuclear factor erythroid 2-related factor 2), EGFR (epidermal growth factor receptor) and via direct structural interactions with ME1 (malic enzyme 1). Upregulated expression of 6PGD provides metabolic as well as defensive advantage to cancer cells, thus, promoting their proliferative and metastatic potential. Moreover, enhanced 6PGD expression also performs key role in development of chemoresistance as well as radiation resistance in cancer. This review aims to discuss the historical timeline and cancer-specific role of 6PGD, pharmacological and genetic inhibitors of 6PGD and 6PGD as prognostic biomarker in order to explore its potential for therapeutic interventions. We anticipate that targeting this imperative supplier of NADPH might serve as tempting avenue to combat the deadly disease like cancer.

2.
Int J Biol Sci ; 16(1): 116-134, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31892850

RESUMO

Peripheral nerve injury is a complex condition with a variety of signs and symptoms such as numbness, tingling, jabbing, throbbing, burning or sharp pain. Peripheral nerves are fragile in nature and can easily get damaged due to acute compression or trauma which may lead to the sensory and motor functions deficits and even lifelong disability. After lesion, the neuronal cell body becomes disconnected from the axon's distal portion to the injury site leading to the axonal degeneration and dismantlement of neuromuscular junctions of targeted muscles. In spite of extensive research on this aspect, complete functional recovery still remains a challenge to be resolved. This review highlights detailed pathophysiological events after an injury to a peripheral nerve and the associated factors that can either hinder or promote the regenerative machinery. In addition, it throws light on the available therapeutic strategies including supporting therapies, surgical and non-surgical interventions to ameliorate the axonal regeneration, neuronal survival, and reinnervation of peripheral targets. Despite the availability of various treatment options, we are still lacking the optimal treatments for a perfect and complete functional regain. The need for the present age is to discover or design such potent compounds that would be able to execute the complete functional retrieval. In this regard, plant-derived compounds are getting more attention and several recent reports validate their remedial effects. A plethora of plants and plant-derived phytochemicals have been suggested with curative effects against a number of diseases in general and neuronal injury in particular. They can be a ray of hope for the suffering individuals.

3.
Analyst ; 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31989131

RESUMO

Gas sensors are important devices used to monitor the type and amount of gas present. Amperometric gas sensors - based on measuring the current upon an applied potential - have been progressing towards miniaturised designs that are smaller, lower cost, faster responding and more robust compared to commercially available sensors. In this work, a planar thin-film electrode device is employed for gas sensing with a thin layer of gel polymer electrolyte (GPE). The GPE consists of a room temperature ionic liquid (RTIL, with two different imidazolium cations and the tetrafluoroborate [BF4]- anion) mixed with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The polymer acts as a scaffold, with the RTIL ions able to flow within the porous percolated channels, resulting in a highly robust gel with high conductivity. The chemical nature of the polymer allows thin-films (ca. 6 µm) to be evenly dropcast onto planar electrode devices, using minimal amounts of material. Remarkably, no significant effect of resistance was observed in the voltammetric response with such thin films. Oxygen (O2) and ammonia (NH3) gases were detected in the concentration ranges 1-20% O2 and 1-10 ppm NH3 in the two GPEs using both linear sweep voltammetry (LSV) and long-term chronoamperometry (LTCA). LTCA was the preferred detection method for both gases due to the steady-state current response compared to the sloping current response from LSV. The thin nature of the film gave fast response times for both gases - less than 10 seconds for O2 and ca. 40 seconds for NH3 - easily rivaling the commercially available porous electrode designs and allowing for continuous monitoring of gas concentrations. These materials appear to be highly promising candidates as gas detection electrolytes in miniaturised devices, with accurate and fast responses in both the cathodic and anodic potential regions.

4.
J Asian Nat Prod Res ; 22(1): 1-16, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29973097

RESUMO

Eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone) is a pharmacologically active flavone which has been isolated from a variety of medicinal plants. Eupatilin is known to possess various pharmacological properties such as anti-cancer, anti-oxidant, and anti-inflammatory. It is speculated that eupatilin could be subjected to structural optimization for the synthesis of derivative analogs to reinforce its efficacy, to minimize toxicity, and to optimize absorption profiles, which will ultimately lead towards potent drug candidates. Although, reported data acclaim multiple pharmacological activities of eupatilin but further experimentations on its molecular mechanism of action are yet mandatory to elucidate full spectrum of its pharmacological activities.

5.
Crit Rev Food Sci Nutr ; 60(3): 351-374, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30614244

RESUMO

Brain is a central and pivotal organ of human body containing the highest lipids content next to adipose tissue. It works as a monitor for the whole body and needs an adequate supply of energy to maintain its physiological activities. This high demand of energy in the brain is chiefly maintained by the lipids along with its reservoirs. Thus, the lipid metabolism is also an important for the proper development and function of the brain. Being a prominent part of the brain, lipids play a vast number of physiological activities within the brain starting from the structural development, impulse conduction, insulation, neurogenesis, synaptogenesis, myelin sheath formation and finally to act as the signaling molecules. Interestingly, lipids bilayer also maintains the structural integrity for the physiological functions of protein. Thus, in light to all of these activities, lipids and its metabolism can be attributed pivotal for brain health and its activities. Decisively, the impaired/altered metabolism of lipids and its intermediates puts forward a key step in the progression of different brain ailments including neurodegenerative, neurological and neuropsychiatry disorders. Depending on their associated underlying pathways, they serve as the potential biomarkers of these disorders and are considered as necessary diagnostic tools. The present review discusses the role and level of altered lipids metabolism in brain diseases including neurodegenerative diseases, neurological diseases, and neuropsychiatric diseases. Moreover, the possible mechanisms of altered level of lipids and their metabolites have also been discussed in detail.

6.
BMC Nephrol ; 20(1): 438, 2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31779583

RESUMO

BACKGROUND: There is paucity of data using direct anti-viral agents (DAA) in patients on maintenance hemodialysis (MHD) infected with HCV-genotype 1 & 3. Aim of the study was to evaluate DAA therapy in patients infected with HCV-genotype 1 & 3 on MHD. METHODS: A prospective open label, parallel, non-randomized interventional trial was conducted in patients with Hepatitis-C on maintenance hemodialysis. Total of Sixty two (62) patients with hepatitis-C on maintenance hemodialysis were screened and 36 patients were enrolled and then equally allocated in 1:1 ratio to group 1 who received 400 mg daily sofosbuvir/ 60 mg daily daclatasvir and group 2 who received thrice a week 400 mg Sofosbuvir and daily 60 mg daclatasvir for 12 weeks. Patients with compensated cirrhosis received therapy for 24 weeks. Relevant data was obtained before, during and after therapy. HCV viral load was assessed at week 4, 8, at end of therapy and 12 weeks after treatment. RESULTS: Eighteen (18) patients were allocated in each group. Three patients in group 1 withdrawn from the study after 2 weeks due to refusal to participate, while one withdrawn in group 2 due to development of adverse effect. Mean age of patients was 47.22 + 14.17 in group 1 and 53.89 + 14.11 in group 2. Genotype 3 was most common in group 1 patients, n = 12 (66.6%), and n = 11 (61.1%) in group 2. All patients in both groups achieved undetectable viral load at 12th week. As per intention to treat analysis overall 29/36 (80.55%) patients achieved SVR (group 1 = 15/18; group 2 = 14/18) and as per-protocol analysis overall 29/32 (90.62%) patients achieved SVR (group 1 = 15/15; group 2 = 14/17). CONCLUSION: Direct acting antiviral therapy using sofosbuvir and declatsavir is highly effective and tolerable in patients with HCV genotype 1 & 3 undergoing maintenance hemodialysis, especially when given daily. TRIAL REGISTRATION: This trial is registered in WHO, International Clinical Trial Registry Platform, through Iranian Registry of Clinical Trials (IRCT) having IRCT ID: IRCT20170614034526N3, registered retrospectively on 2019-03-08.

7.
Pak J Pharm Sci ; 32(4(Supplementary)): 1761-1766, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31680070

RESUMO

Peripheral nerve injury is a complex condition which results in restricted physical activity. Despite the tremendous efforts to figure out effective remedies, the complete functional retrieval is still a goal to be achieved. So, the need of hour is the exploration of potential natural compounds to recover this functional loss. Here, we have investigated the role of a local plant "Neurada procumbens" in ameliorating the functional recovery after an induced nerve compression injury in a mouse model. A dose of N. procumbens (50mg/kg of body weight) was administered orally from the day of injury to onwards. The motor functional recovery was assessed by evaluating muscle grip strength and sciatic functional index; while the sensory functions were gauged by the hotplate test. The serological parameters were carried out to analyze the effect of N. procumbens on oxidative stress level. The recovery of sensory and motor functions was significantly improved and perceived earlier in the treatment group. Moreover, the elevated antioxidant level was statistically significant in the treatment group. These results indicate that the supplementation of N. procumbens accelerates functional recovery after sciatic nerve crush injury.

8.
Int J Biol Sci ; 15(10): 2256-2264, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31592132

RESUMO

Nature has generously offered life-saving therapies to mankind by providing evolutionarily optimized drug-like entities in the form of natural products. These splendid gifts of nature have served as most suitable candidates for anti-cancer drug discovery due to their pleiotropic activity on target molecules. This review aims to provide an update on the natural sources and bioactivities of such gifts from nature, salvianolic acid A & B, which are major bioactive constituents of a traditional Chinses medicinal herb, Salvia miltiorrhiza. Salvianolic acid A & B have been reported to owe anti-cancer, anti-inflammatory and cardioprotective activities. Currently salvianolic acids have been emerged as potent anti-cancer molecules. Salvianolic acid A & B fight cancer progression by prompting apoptosis, halting cell cycle and adjourning metastasis by targeting multiple deregulated signaling networks of cancer. Moreover, salvianolic acid A & B display potency towards sensitizing cancer cells to chemo-drugs. The review purposes that salvianolic acid A & B supply a novel opportunity for drug discovery but further experimentation is mandatory to embellish the knowledge of their pharmacological usage and to access their toxicological limits in order to establish these compounds as potential multitarget future drugs.

9.
J Food Biochem ; 43(9): e12983, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31489666

RESUMO

Peripheral nerve injury is one of the major health concerns of the present era which can lead to the long-lasting disability and even demise. Currently, no effective and side effect free remedy exists and exploration of effective therapeutic strategies to regain functional outcome is a need of hour. In the present study, we used BALB/c mice (N = 14 age, 10-12 weeks & weight 32-34 g) that were divided into two groups: Normal chow (n = 7) and Fennel chow (n = 7) group. Here, we have explored the role of crude Foeniculum vulgare mill seeds in promoting functional recovery following a mechanical insult to the sciatic nerve by an oral administration of a crude dose of 500 mg/kg BW. The recovery of both sensory and motor functions was significantly (p > .05) accelerated in the treatment group, assessed by behavioral analyses alongside total antioxidant capacity increase. Conclusively, F. vulgare can be a potential therapeutic candidate for accelerating functional recovery after peripheral nerve injury. PRACTICAL APPLICATIONS: The outcomes of study have vital practical application both for scientists and consumers. The therapeutic role of phytochemicals on functional recovery has not been explored yet. This study will help figure out plant based regimen as booster for brain health and intervention against traumatic nerve injuries. Moreover, it may also attract the food and pharmaceutical industries to formulate cost effective therapeutic products. Likewise, it can prove instrumental for scientists for advance research on this aspect with more mechanistic targets.

10.
Biomed Res Int ; 2019: 5854315, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31467899

RESUMO

Nature, a vast reservoir of pharmacologically active molecules, has been most promising source of drug leads for the cure of various pathological conditions. Formononetin is one of the bioactive isoflavones isolated from different plants mainly from Trifolium pratense, Glycine max, Sophora flavescens, Pycnanthus angolensis, and Astragalus membranaceus. Formononetin has been well-documented for its anti-inflammatory, anticancer, and antioxidant properties. Recently anticancer activity of formononetin is widely studied. This review aims to highlight the pharmacological potential of formononetin, thus providing an insight of its status in cancer therapeutics. Formononetin fights progression of cancer via inducing apoptosis, arresting cell cycle, and halting metastasis via targeting various pathways which are generally modulated in several cancers. Although reported data acclaims various biological properties of formononetin, further experimentation on mechanism of its action, medicinal chemistry studies, and preclinical investigations are surely needed to figure out full array of its pharmacological and biological potential.


Assuntos
Proliferação de Células/efeitos dos fármacos , Isoflavonas/farmacologia , Neoplasias/tratamento farmacológico , Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Humanos , Isoflavonas/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Soja/química , Trifolium/química
11.
Bioorg Chem ; 91: 103138, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31446329

RESUMO

In the designed research work, a series of 2-furoyl piperazine based sulfonamide derivatives were synthesized as therapeutic agents to target the Alzheimer's disease. The structures of the newly synthesized compounds were characterized through spectral analysis and their inhibitory potential was evaluated against butyrylcholinesterase (BChE). The cytotoxicity of these sulfonamides was also ascertained through hemolysis of bovine red blood cells. Furthermore, compounds were inspected by Lipinki Rule and their binding profiles against BChE were discerned by molecular docking. The protein fluctuations in docking complexes were recognized by dynamic simulation. From our in vitro and in silico results 5c, 5j and 5k were identified as promising lead compounds for the treatment of targeted disease.

12.
Pak J Pharm Sci ; 32(3 (Supplementary)): 1145-1154, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31326872

RESUMO

Survivin (IAP proteins) is considered as a significant target for anticancer drug research owing to its upregulation in tumor cells to mediate resistance to apoptotic stimulus. The current study aimed to investigate phytochemicals as inhibitors of survivin with caspases to reactivate the functioning of caspases through molecular docking. The compounds namely 2(R), 4(R)-dihydroxypyrrolidine, 4-hydroxy-2-(4-methoxyphenyl)-1,1-dioxo-3,4-dihydrothieno[3,2-e]thiazine-6-sulfonamide, 2,3-Diketo-L-gulonic acid, (3-hydroxy-2-octadeca-9,12-dienoyloxypropyl) octadecanoate, 2-[[4-[[4-[(4-formamido-1-methylimidazole-2-carbonyl)amino]-1-methylimidazole-2-carbonyl]amino]-1-methylimidazole-2-carbonyl]amino]ethyl-dimethylazanium, Picolinic acid and (2-Hydroxy-5-nitrophenyl) dihydrogen phosphate successfully bind inside the pocket of survivin. ADMETsar was used to evaluate the anticancer potential of selected compounds. These compounds can be proposed as effective inhibitors, disrupting the survivin-caspases interaction and reactivating the caspases function of apoptosis. The study might facilitate the development of cost-effective and natural drugs against cancer. However, further validation is essential for confirmation of its drug efficacy and bio-compatibility.

13.
Pak J Pharm Sci ; 32(3 (Supplementary)): 1145-1154, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31303583

RESUMO

Survivin (IAP proteins) is considered as a significant target for anticancer drug research owing to its upregulation in tumor cells to mediate resistance to apoptotic stimulus. The current study aimed to investigate phytochemicals as inhibitors of survivin with caspases to reactivate the functioning of caspases through molecular docking. The compounds namely 2(R), 4(R)-dihydroxypyrrolidine, 4-hydroxy-2-(4-methoxyphenyl)-1,1-dioxo-3,4-dihydrothieno[3,2-e]thiazine-6-sulfonamide, 2,3-Diketo-L-gulonic acid, (3-hydroxy-2-octadeca-9,12-dienoyloxypropyl) octadecanoate, 2-[[4-[[4-[(4-formamido-1-methylimidazole-2-carbonyl)amino]-1-methylimidazole-2-carbonyl]amino]-1-methylimidazole-2-carbonyl]amino]ethyl-dimethylazanium, Picolinic acid and (2-Hydroxy-5-nitrophenyl) dihydrogen phosphate successfully bind inside the pocket of survivin. ADMETsar was used to evaluate the anticancer potential of selected compounds. These compounds can be proposed as effective inhibitors, disrupting the survivin-caspases interaction and reactivating the caspases function of apoptosis. The study might facilitate the development of cost-effective and natural drugs against cancer. However, further validation is essential for confirmation of its drug efficacy and bio-compatibility.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Compostos Fitoquímicos/farmacologia , Survivina/antagonistas & inibidores , Survivina/química , Antineoplásicos Fitogênicos/farmacocinética , Antineoplásicos Fitogênicos/toxicidade , Caspases/metabolismo , Simulação por Computador , Humanos , Simulação de Acoplamento Molecular , Terapia de Alvo Molecular , Compostos Fitoquímicos/farmacocinética , Compostos Fitoquímicos/toxicidade , Conformação Proteica , Survivina/metabolismo , Distribuição Tecidual
14.
Int J Biol Sci ; 15(8): 1600-1609, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31360103

RESUMO

Natural products, an infinite treasure of bioactive scaffolds, have provided an excellent reservoir for the discovery of drugs since millennium. These naturally occurring, biologically active and therapeutically effective chemical entities have emerged as novel paradigm for the prevention of various diseases. This review aims to give an update on the sources as well as pharmacological profile of curcumol, a pharmacologically active sesquiterpenoid, which is an imperative bioactive constituent of several plants mainly from genus Curcuma. Curcumol has potential to fight against cancer, oxidative stress, neurodegeneration, microbial infections, and inflammation. Curcumol has been documented as potent inducer of apoptosis in numerous cancer cells via targeting key signaling pathways as MAPK/ERK, PI3K/Akt and NF-κB which are generally deregulated in several cancers. The reported data reveals multitarget activity of curcumol in cancer treatment suggesting its importance as anticancer drug in future. It is speculated that curcumol may provide an excellent opportunity for the cure of cancer but further investigations on mechanism of its action and preclinical trials are still mandatory to further validate the potential of this natural cancer killer in anticancer therapies.

16.
IUBMB Life ; 71(10): 1418-1427, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31169978

RESUMO

Altered enzymatic machineries are a substantial biochemical characteristic of tumor cell metabolism that switch metabolic profile from oxidative phosphorylation to amplified glycolysis as well as increased lactate production under hypoxia conditions. Reprogrammed metabolic profile is an emerging hallmark of cancer. Overexpression of several glycolytic enzymes and glucose transporters has been reported in 24 different types of cancers that represent approximately 70% of all the cancer cases around the globe. Thus, targeting glycolytic enzymes could serve as tempting avenue for drug design against cancer. Phosphoglycerate mutase 1 (PGAM1) is an important glycolytic enzyme that catalyzes the conversion of 3-phosphoglycerate to 2-phosphoglycerate. Recent investigations have revealed the overexpression of PGAM1 in several human cancers that is linked with tumor growth, survival, and invasion. The aim of this review is to update scientific research network with cancer-specific role of PGAM1 to elucidate its capability as bonafide therapeutic target for cancer therapy. Moreover, we have also summarized the reported genetic and pharmacological inhibitors of PGAM1. This study suggests that further investigations on PGAM1 should focus on the exploration of molecular mechanisms of PGAM1 overexpression in development of cancer, assessment of biosafety profiles of known inhibitors of PGAM1, and utilization of PGAM1 inhibitors in combinatorial therapies. These future studies will surely support the unbiased strategies for the development of novel PGAM1 inhibitors for cancer therapies.

17.
Anal Chim Acta ; 1072: 35-45, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31146863

RESUMO

From a safety perspective, it is vital to have fast responding gas sensors for toxic and explosive gases in the event of a gas leak. Amperometric gas sensors have been developed for such a purpose, but their response times are often relatively slow - on the order of 50 seconds or more. In this work, we have developed sensors for hydrogen gas that demonstrate ultra-fast response times. The sensor consists of an array of gold microchannel electrodes, electrodeposited with platinum nanoparticles (PtNPs) to enable hydrogen electroactivity. Very thin layers (∼9 µm) of room temperature ionic liquids (RTILs) result in an extremely fast response time of only 2 s, significantly faster than the other conventional electrodes examined (unmodified Pt electrode, and PtNP modified Au electrode). The RTIL layer in the microchannels is much thinner than the channel length, showing an interesting yet complex diffusion pattern and characteristic thin-layer behavior. At short times (e.g. on the timescale of cyclic voltammetry), the oxidation current is smaller and steady-state in nature, compared to macrodisk electrodes. At longer times (e.g. using long-term chronoamperometry), the diffusion layer is large for all surfaces and extends to the liquid/gas phase boundary, where the gas is continuously replenished from the flowing gas stream. Thus, the current response is the largest on the microchannel electrode, resulting in the highest sensitivity and lowest limit of detection for hydrogen. These microchannel electrodes appear to be highly promising surfaces for the ultrafast detection of hydrogen gas, particularly at relevant concentrations close to, or below, the lower explosive limit of 4 vol-% H2.

18.
Molecules ; 24(12)2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31200495

RESUMO

Neurodegenerative and neuropsychiatric diseases are characterized by the structural and functional abnormalities of neurons in certain regions of the brain. These abnormalities, which can result in progressive neuronal degeneration and functional disability, are incurable to date. Although comprehensive efforts have been made to figure out effective therapies against these diseases, partial success has been achieved and complete functional recovery is still not a reality. At present, plants and plant-derived compounds are getting more attention because of a plethora of pharmacological properties, and they are proving to be a better and safer target as therapeutic interventions. This review aims to highlight the roles of tannins, 'the polyphenol phytochemicals', in tackling neurodegenerative diseases including Alzheimer's and Parkinson's diseases as well as neuropsychiatric disorders like depression. Among the multifarious pharmacological properties of tannins, anti-oxidative, anti-inflammatory, and anti-cholinesterase activities are emphasized more in terms of neuroprotection. The current review also throws light on mechanistic pathways by which various classes of tannins execute neuroprotective effects. Despite their beneficial properties, some harmful effects of tannins have also been elaborated.


Assuntos
Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/uso terapêutico , Taninos/química , Taninos/uso terapêutico , Doença de Alzheimer/tratamento farmacológico , Humanos , Neuropsiquiatria , Doença de Parkinson/tratamento farmacológico , Compostos Fitoquímicos/química , Compostos Fitoquímicos/uso terapêutico
19.
Polymers (Basel) ; 11(6)2019 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-31212840

RESUMO

The impact strength and surface properties of polymeric materials are of critical importance in various engineering applications. Friction stir processing (FSP) is a novel method for the fabrication of composite materials with superior mechanical properties. The main objective of this study is to investigate the impact strength and Rockwell hardness of UHMW polyethylene composites reinforced with nano-hydroxyapatite particles fabricated through FSP. The spindle speed (ω), tool traverse speed (f), volume fraction (v) of strengthening material and shoulder temperature (T) were key processing parameters. The analysis of variance (ANOVA) indicated that the selected processing parameters were significant. Microscopic investigations unveiled that high levels of (v, f) and low levels of (T, ω) caused agglomeration of the reinforcing particles and induced voids and channels, which consequently reduced the impact strength and hardness of the manufactured composite. However, medium conditions of processing parameters exhibited better distribution of particles with minimum defects, and hence resulted in better mechanical properties. Finally, the models to predict the impact strength and hardness are proposed and verified. Sets of process parameters favorable to maximize the impact strength and Rockwell hardness were worked out, which were believed to increase the impact strength, Rockwell hardness number, and ultimate tensile strength by 27.3%, 5.7%, and 11.2%, respectively.

20.
J Nanosci Nanotechnol ; 19(11): 7229-7235, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31039880

RESUMO

A single step fast track method is proposed to determine melamine based on strong hydrogen bonding between exocyclic amine group in melamine moiety and hydroxyl group of tannic acid (TA); acting as reducing and functionalizing agent for synthesis of gold nanoparticles (Au NPs). The proposed strategy is facile and highly time saving; as the detection of melamine with labelfree gold nanoparticles was accomplished within five minutes. The colorimetric probe exhibits high detection limit of 8 nM for melamine determination in raw milk, which is very low as compared to other capping ligands employed for Au NPs such as borohydride, citrate and 3,5-dihydroxybenzoic acid. The results show a highly sensitive linear range (0.03-2.5 µM) between absorption ratio and concentration of melamine with a correlation coefficient of 0.991. Proposed methodology is proven effective for on-site screening without using costly instrumentation.

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