Super absorption of solar energy using a plasmonic nanoparticle based CdTe solar cell

Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction. Here, a comprehensive study of solar energy enhancement in a cadmium telluride (CdTe) thin-film solar cell based on the simple design of a square array of plasmonic titanium nanoparticles, has been reported. The excitation of localized plasmons in the metallic nanostructures together with the antireflection coating (ARC) significantly enhances the absorption of photons in the active CdTe layer. The proposed structure attained super absorption with a mean absorbance of more than 97.27% covering a wide range from visible to near-infrared (i.e., from 300 nm to 1200 nm), presenting a 90% absorption bandwidth over 900 nm, and the peak absorption is up to 99.9%. For qualitative analysis, the photocurrent density is also estimated for AM 1.5 solar illumination (global tilt), whose value reaches 40.36 mA cm⁻², indicating the highest value reported to date. The impact of nanoparticle dimensions, various metal materials, shapes, and random arrangement of nanoparticles on optical absorption are discussed in detail. Moreover, the angle insensitivity is essentially validated by examining the absorption performance with oblique incidences and it is found that the solar cell keeps high absorption efficiency even when the incidence angle is greater than 0°. Therefore, these findings suggest that the proposed broadband structure has good prospect in attaining high power conversion efficiency while reducing the device cost.

Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction.     

Chlorophyll derivatives can be an efficient weapon in the fight against dengue

Dengue, a mosquito-borne viral infection, is one of the major public health concerns in the tropical and subtropical regions of the world. Approximately, 2.5 billion people across the world are at risk from dengue and 50 to 100 million new infections of dengue occur annually. There is yet no vaccine or medicine available against dengue, and treatment remains only supportive. Targeting its vector by a combination of biological and chemical approaches and management of breeding sites are currently the only existing approaches to control or eliminate dengue. Chlorophyll derivatives like chlorophyllin and pheophorbide have been reported as effective natural photosensitizers against larvae of several insects including flies. Chlorophyll derivatives were also reported effective against larval stages of freshwater snails as well as against certain parasites of fish. This article briefly discusses the possible application of chlorophyll derivatives in controlling dengue vectors and hence the disease itself. Chlorophyll derivatives can prove to be a good contributor in an integrated approach against dengue.     

Renin angiotensin system modulates mTOR pathway through AT2R in HIVAN

Mammalian target of rapamycin (mTOR) has been reported to contribute to the development of HIV-associated nephropathy (HIVAN). We hypothesized that HIV may be activating renal tissue mTOR pathway through renin angiotensin system (RAS) via Angiotensin Receptor Type II receptor (AT2R). Renal tissues of Vpr transgenic and Tg26 (HIVAN) mice displayed enhanced phosphorylation of mTOR and p70S6K. Aliskiren, a renin inhibitor attenuated phosphorylation of both mTOR and p70S6K in renal tissues of HIVAN mice. Interestingly, Angiotensin Receptor Type I (AT1R) blockade did not modulate renal tissue phosphorylation of mTOR in HIVAN mice; on the other hand, AT2R blockade attenuated renal tissue phosphorylation of mTOR in HIVAN mice. In vitro studies, both renin and Ang II displayed enhanced mouse tubular cell (MTC) phosphorylation of p70S6K in a dose dependent manner. HIV/MTC also displayed enhanced phosphorylation of both mTOR and p70S6K; interestingly this effect of HIV was further enhanced by losartan (an AT1R blocker). On the other hand, AT2R blockade attenuated HIV-induced tubular cell phosphorylation of mTOR and p70S6K, whereas, AT2R agonist enhanced phosphorylation of mTOR and p70S6K. These findings indicate that HIV stimulates mTOR pathway in HIVAN through the activation of renin angiotensin system via AT2R.     

Natural compounds with xanthine oxidase inhibitory activity: A review

Hyperuricemia (HUA), a disease due to an elevation of body uric acid level and responsible for various diseases such as gout, cardiovascular disorders, and renal failure, is a major ground debate for the medical science these days. Considering the risk factors linked with allopathic drugs for the treatment of this disease, the debate has now become a special issue. Previously, we critically discussed the role of dietary polyphenols in the treatment of HUA. Besides dietary food plants, many researchers figure out the tremendous effects of medicinal plants‐derived phytochemicals against HUA. Keeping in mind all these aspects, we reviewed all possible managerial studies related to HUA through medicinal plants (isolated compounds). In the current review article, we comprehensively discussed various bioactive compounds, chemical structures, and structure–activity relationship with responsible key enzyme xanthine oxidase.     

Leishmania-induced biphasic ceramide generation in macrophages is crucial for uptake and survival of the parasite

The initial macrophage-Leishmania donovani interaction results in the formation of membrane platforms, termed lipid rafts, that help in the entry of the parasite. Therefore, it is imperative that the parasite designs a strategy to modulate its uptake and survival within the macrophages. Herein, we report Leishmania-triggered biphasic ceramide generation. In the first phase, L. donovani promastigotes induce activation of acid sphingomyelinase (ASMase), which catalyzes the formation of ceramide from sphingomyelin. Inhibition of ASMase resulted in reduced uptake and infection with the parasite. In the second phase, de novo synthesis generates ceramide that reduces the cellular cholesterol level and displaces the cholesterol from the membrane, leading to enhanced membrane fluidity, disruption of rafts, and impaired antigen-presentation to the T cells. The results reveal a novel role for ceramide in the perspective of L. donovani infection and help formulate an antileishmanial strategy that can possibly be applied to other intracellular infections as well.     

INAUGURAL ARTICLE by a Recently Elected Academy Member:Impact of pyrethroid resistance on operational malaria control in Malawi

The impact of insecticide resistance on insect-borne disease programs is difficult to quantify. The possibility of eliminating malaria in high-transmission settings is heavily dependent on effective vector control reducing disease transmission rates. Pyrethroids are the dominant insecticides used for malaria control, with few options for their replacement. Their failure will adversely affect our ability to control malaria. Pyrethroid resistance has been selected in Malawi over the last 3 y in the two major malaria vectors Anopheles gambiae and Anopheles funestus, with a higher frequency of resistance in the latter. The resistance in An. funestus is metabolically based and involves the up-regulation of two duplicated P450s. The same genes confer resistance in Mozambican An. funestus, although the levels of up-regulation differ. The selection of resistance over 3 y has not increased malaria transmission, as judged by annual point prevalence surveys in 1- to 4-y-old children. This is true in areas with long-lasting insecticide-treated nets (LLINs) alone or LLINs plus pyrethroid-based insecticide residual spraying (IRS). However, in districts where IRS was scaled up, it did not produce the expected decrease in malaria prevalence. As resistance increases in frequency from this low initial level, there is the potential for vector population numbers to increase with a concomitant negative impact on control efficacy. This should be monitored carefully as part of the operational activities in country.The push for malaria elimination and eventual eradication will be heavily dependent on our ability to reduce disease transmission. A recent editorial suggests that we have the tools to take on this challenge in African malaria heartlands (1). This is predicated on ensuring that vector control prevention and drug treatment tools are fully deployed, reaching every person at risk. There will need to be improved delivery of these tools and better clinical management of malaria cases. In highly endemic areas our ability to reduce malaria transmission will be dependent on vector control, before the focus can shift to killing the parasite in infected people. Two forms of vector control, indoor residual spraying (IRS) and the distribution of long-lasting insecticide-treated nets (LLINs) have been demonstrated to reduce transmission when properly deployed against insecticide susceptible mosquito populations. The use of both interventions has dramatically increased since 2000 in many malaria endemic countries, with increased donor funding to attain the Roll Back Malaria targets and support the malaria elimination agenda (2).IRS and LLINs function by reducing the female mosquito daily survival rate and human biting frequency. Pyrethroids are the only insecticides recommended for use on LLINs, and only four chemical classes of insecticides that attack two target sites are available for IRS, and again pyrethroids dominate the IRS market. Resistance to pyrethroids has been selected in Anopheles gambiae and Anopheles funestus, the major African malaria vectors, although the frequency and level (fold) resistance conferred can vary dramatically. The impact of this resistance on the ability of either control intervention to reduce disease transmission is poorly understood, and current monitoring and evaluation practices are not sufficiently robust to assess this unless catastrophic failures occur. The perceived threat of pyrethroid resistance is now sufficiently high for the World Health Organization (WHO) to convene an international multidonor effort to counteract this.Operationally significant pyrethroid resistance has the potential to limit effective malaria control, owing to the small number of alternative public health insecticides. Pyrethroid resistance in malaria vectors has increased dramatically over the last decade (3, 4), particularly in Africa, where the bulk of malaria-related mortality occurs. Typically resistance is monitored by bioassays, for which the WHO has defined a diagnostic dosage for each insecticide that kills susceptible anopheline mosquitoes (5). Mosquitoes surviving the diagnostic dosage are an indication that resistance has been selected and that an operational problem may be developing, but bioassays alone do not signify control failure.Little operational monitoring of the underlying mechanisms of resistance occurs. Two mechanisms are predominantly responsible for insecticide resistance: changes in the insecticide target site, reducing binding of the insecticide, and increases in the rate at which the insecticide is metabolized (6). Information on the resistance mechanisms is more predictive than bioassays, providing information on the level of resistance and potential cross-resistance between insecticides. For example, two common mutations in the sodium channel convey low-level resistance to pyrethroids and higher-level resistance to dichlorodiphenyltrichloroethane (DDT) in An. gambiae (7, 8), whereas a cytochrome P450-based metabolic regulatory mechanism conveys very high-level pyrethroid and low-level carbamate resistance in An. funestus (9).Vector control interventions are being rapidly scaled up in Malawi, where malaria is highly endemic. Malaria accounts for 34% of all outpatient hospital visits and is the main cause of hospital admissions in children aged <5 y (10). Before 2007 sporadic WHO bioassays were undertaken, which indicated that the two major malaria vectors, An. gambiae and An. funestus, remained fully susceptible to pyrethroids. In 2007 pyrethroid-impregnated LLINs were distributed through antenatal and under-5 clinics at district and central hospitals countrywide. The numbers distributed were sufficient to achieve the Roll Back Malaria targets of 80% of pregnant women and children aged <5 y sleeping under a treated net. In 2008, a pilot study of IRS with the pyrethroid lambda cyhalothrin (ICON, Syngenta) was initiated in Nkhota Khota District, supported by the President’s Malaria Initiative (PMI). The initial program targeted 26,950 houses, and was expanded to 74,772 houses in 2009. Approximately 4 million LLINs were procured and ∼2 million distributed during this time. In 2010 the PMI-supported IRS was expanded to cover the whole of Nkohta Khota district, and the Malawian Ministry of Health supported IRS in a further six districts.A series of sentinel sites were established during this period to track the effect of this rapid increase in insecticide selection pressure on the local vectors and assess any impact on malaria transmission. This was particularly pertinent owing to the high levels of pyrethroid resistance reported in the southern part of neighboring Mozambique in An. funestus, which had prompted a switch from pyrethroids to carbamates or DDT for IRS in the Lubombo Spatial Development Initiative area of Mozambique (11, 12).     

Biomechanical comparison of locked plating and spiral blade retrograde nailing of supracondylar femur fractures

Objective

Biomechanical comparison between locked plating and retrograde nailing of supracondylar femur fractures with simulated postoperative weight-bearing.

Methods

The Locking Condylar Plate (LCP) and Retrograde/Antegrade EX Femoral Nail (RAFN) were tested using 10 paired elderly cadaveric femurs, divided into Normal and Low Bone Mineral Density (BMD) groups, with a simulated AO/OTA type 33-A3 supracondylar femur fracture. Each specimen was subjected to 200,000 loading cycles in an attempt to simulate six weeks of postoperative recovery with full weight-bearing for an average individual. The construct's subsidence due to cyclic loading, and axial stiffness before and after the cyclic loading were measured and their correlation with BMD was studied. The two implants were compared in a paired study within each BMD group.

Results

LCP constructs showed higher axial stiffness compared to RAFN for both Normal and Low BMD groups (80% and 57%, respectively). After cyclic loading, axial stiffness of both constructs decreased by 20% and RAFN constructs resulted in twice as much subsidence (1.9 ± 0.6 mm). Two RAFN constructs with Low BMD failed after a few cycles whereas the matched pairs fixed with LCP failed after 70,000 cycles.

Conclusions

The RAFN constructs experienced greater subsidence and reduced axial stiffness compared to the LCP constructs. In Low BMD specimens, the RAFN constructs had a higher risk of failure.