Effects of a newly developed palm-based processing aid and curing systems on the physical properties of nitrile rubber composites

Researches on developing renewable and eco-friendly processing aid are still on-going in the effort of replacing conventional petroleum-based processing aid. In this study, the effects of a palm-based processing aid (Bio) and curing systems on the physical properties of nitrile rubber (NBR) composites were evaluated. Curing systems studied were conventional (CV), semi-efficient (SEV) and efficient (EV) curing systems. It was found that regardless of the curing systems, the addition of Bio reduced the delta torque, cure rate index, glass transition temperature and loss tangent of the NBR composites. Reduction of delta torque by Bio resulted in lower tensile modulus (M100) and higher elongation at break (EB) of composites. Hardness, swelling index and compression set were also higher with the incorporation of Bio. The effects of curing system were also prominent in which using CV cure system leads to higher M100 and hardness and lower EB and compression sets. Excellent aging properties are crucial as it predicts the properties of the composite during service. After accelerated aging, results revealed that the effects of curing systems were significant on the retention of M100 and compression set of NBR composites where the SEV cured composites showed the highest retention of M100 and the lower compression set values. NBR composite with Bio, using a semi-efficient curing system was found to have the best aging properties compared to other composites

Apoptotic Effects of Chrysin in Human Cancer Cell Lines

Chrysin is a natural flavonoid currently under investigation due to its important biological anti-cancer properties. In most of the cancer cells tested, chrysin has shown to inhibit proliferation and induce apoptosis, and is more potent than other tested flavonoids in leukemia cells, where chrysin is likely to act via activation of caspases and inactivation of Akt signaling in the cells. Moreover, structure-activity relationships have revealed that the chemical structure of chrysin meets the key structural requirements of flavonoids for potent cytotoxicity in leukemia cells. It is possible that combination therapy or modified chrysin could be more potent than single-agent use or administration of unmodified chrysin. This study may help to develop ways of improving the effectiveness of chrysin in the treatment of leukemia and other human cancers in vitro

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Prospective, multicentre study of screening, investigation and management of hyponatraemia after subarachnoid haemorrhage in the UK and Ireland

Background: Hyponatraemia often occurs after subarachnoid haemorrhage (SAH). However, its clinical significance and optimal management are uncertain. We audited the screening, investigation and management of hyponatraemia after SAH. Methods: We prospectively identified consecutive patients with spontaneous SAH admitted to neurosurgical units in the United Kingdom or Ireland. We reviewed medical records daily from admission to discharge, 21 days or death and extracted all measurements of serum sodium to identify hyponatraemia (<135 mmol/L). Main outcomes were death/dependency at discharge or 21 days and admission duration >10 days. Associations of hyponatraemia with outcome were assessed using logistic regression with adjustment for predictors of outcome after SAH and admission duration. We assessed hyponatraemia-free survival using multivariable Cox regression. Results: 175/407 (43%) patients admitted to 24 neurosurgical units developed hyponatraemia. 5976 serum sodium measurements were made. Serum osmolality, urine osmolality and urine sodium were measured in 30/166 (18%) hyponatraemic patients with complete data. The most frequently target daily fluid intake was >3 L and this did not differ during hyponatraemic or non-hyponatraemic episodes. 26% (n/N=42/164) patients with hyponatraemia received sodium supplementation. 133 (35%) patients were dead or dependent within the study period and 240 (68%) patients had hospital admission for over 10 days. In the multivariable analyses, hyponatraemia was associated with less dependency (adjusted OR (aOR)=0.35 (95% CI 0.17 to 0.69)) but longer admissions (aOR=3.2 (1.8 to 5.7)). World Federation of Neurosurgical Societies grade I–III, modified Fisher 2–4 and posterior circulation aneurysms were associated with greater hazards of hyponatraemia. Conclusions: In this comprehensive multicentre prospective-adjusted analysis of patients with SAH, hyponatraemia was investigated inconsistently and, for most patients, was not associated with changes in management or clinical outcome. This work establishes a basis for the development of evidence-based SAH-specific guidance for targeted screening, investigation and management of high-risk patients to minimise the impact of hyponatraemia on admission duration and to improve consistency of patient care

Reactions of epoxidized natural rubber with palm oil-based alkyds and medium-chain-lenght polyhydroxyalkanoates / Lee Siang Yin

Actinomycetes are widespread in marine ecosystem. They are of interest in research field as they are capable to produce bioactive secondary metabolites which can be developed into useful pharmaceutical products. An example of the product is antibiotics which can be used to treat infectious diseases. The potential of antibacterial and antifungal activity of eleven marine derived actinomycetes from the genus Streptomyces were studied. They were tested against bacteria Enterobacter faecalis, Staphylococcus aureus, Bacillus subtilis, Pleisiomonas shigelloides and Pseudomonas aeruginosa and fungi Candida parapsilosis and Candida albicans. Primary screening by the cross streak method and secondary screening by diffusion using paper disc method with crude extracts were carried out in this study. Media optimization was also carried out to optimize the media for production of bioactive secondary metabolites. Of the eleven strains studied, strain T53 exhibited the strongest antibacterial activity against E. faecalis. Gram-positive bacteria were more susceptible than Gram-negative bacteria. Strain T53, T52, T9 and T12 had broad spectrum activities. Strain T53, T16,T15 and T4 exhibited antifungal activity against all tested fungi. Yeast extract-malt extract agar (ISP2) and agitated fermentation were the best media and the best fermentation condition, respectively

FORMULATION AND EVALUATION OF TOPICAL PENTOXIFYLLINE-HYDROXYPROPYL METHYLCELLULOSE GELS FOR WOUND HEALING APPLICATION

Objectives: Oral pentoxifylline shows modest, non-significant effect on the healing rates of chronic wounds. The present research aimed to formulate topical pentoxifylline-hydroxypropyl methylcellulose (HPMC) gels and evaluate their physico-chemical properties, in vitro release characteristics and in vivo wound healing effects. Methods: Six gel formulations containing pentoxifylline (F1-F6) were prepared using HPMC with varying grades and concentrations. The physicochemical properties of gel formulations were evaluated in term of drug content, spreadability, rheological properties, swelling, and release characteristics. The efficacy of optimized formulation was further evaluated using in vivo excision wound models in rats. Results:  The spreadability, flow index and swelling percentage of gel formulations ranged 10.71-12.24 gcm/sec, 0.33-0.91 and 148.61-8011.61%, respectively. The rheological study of the prepared formulations exhibited pseudoplastic behavior, which is a characteristic feature of topical gels. Swelling results of F5 and F6 deduced that the cross-linked structures were formed between the polymeric chains. The in vitro drug release profiles of all formulations were found to be followed Higuchi model. The in vivo evaluation performed using rat excision wound model showed significant difference (P < 0.05) in the percentage reduction of wound size between treatment and control groups. The treatment group exhibited complete healing by day 13 as compared with day 15 in the control group. Conclusions:  These findings indicated that F5 gel formulation had demonstrated effective release profile for pentoxifylline. The in vivo results confirmed that F5 has pronounced wound healing effects when employed topically. Â&nbsp

POLYMERIC MATERIALS AS PLATFORMS FOR TOPICAL DRUG DELIVERY: A REVIEW

With the emergence of novel and more effective drug therapies, increased importance is being placed upon the drug delivery technology. Topical formulations are attractive alternatives to oral formulations and offer several advantages, such as avoiding first-pass hepatic metabolism and gastric degradation. The major obstacle to drug delivery across the skin (transdermal) is the barrier nature of the skin which limits permeation of molecules. A wide range of polymeric materials is currently available for drug delivery to and across the skin. The synthetic polymers such as polyesters, polyamides, polyurethanes, polyanhydrides and poly(ortho-esters) display advantages of reproducibility of synthesis, a range of material properties and biodegradability, whereas agro-polymers like polysaccharides, proteins and lipids have already shown great promise in terms of type of material, range of properties, processing technique and biocompatibility. This review article summarizes features of different polymers and their potential applications in topical drug delivery system

Proton-assisted redox-based three-terminal memristor for synaptic device applications

Emerging technologies, i.e., spintronics, 2D materials, and memristive devices, have been widely investigated as the building block of neuromorphic computing systems. Three-terminal memristor (3TM) is specifically designed to mitigate the challenges encountered by its two-terminal counterpart as it can concurrently execute signal transmission and memory operations. In this work, we present a complementary metal-oxide-semiconductor-compatible 3TM with highly linear weight update characteristics and a dynamic range of ∼15. The switching mechanism is governed by the migration of oxygen ions and protons in and out of the channel under an external gate electric field. The involvement of the protonic defects in the electrochemical reactions is proposed based on the bipolar pulse trains required to initiate the oxidation process and the device electrical characteristics under different humidity levels. For the synaptic operation, an excellent endurance performance with over 256k synaptic weight updates was demonstrated while maintaining a stable dynamic range. Additionally, the synaptic performance of the 3TM is simulated and implemented into a four-layer neural network (NN) model, achieving an accuracy of ∼92% in MNIST handwritten digit recognition. With such desirable conductance modulation characteristics, our proposed 3T-memristor is a promising synaptic device candidate to realize the hardware implementation of the artificial NN.Agency for Science, Technology and Research (A*STAR)This work was supported by a RIE2020 ASTAR AME IAF-ICP grant (no. I1801E0030)