HVAC Systems with Low Global Warming Potential Refrigerants: A Case Study

The objective of this case study is three-fold: (1) identify promising alternative refrigerants with lower global warming potential (GWP); (2) among those, select refrigerant(s) that could be “drop-in” replacements for R-410A and would not require significant system redesign or compressor changes — with the exception of minimal changes such as lubricating fluid and expansion valves; (3) evaluate the impact of another easy-to-implement option: replacing lower-efficiency, permanently split capacitor (PSC) condenser fans and evaporator blower motors with electronically commutated motors (ECM) for additional system efficiency improvements. This study leverages the steady-state heat pump design model (HPDM) developed by the Department of Energy (DOE) and the Oak Ridge National Laboratory (ORNL) to demonstrate three key findings: (1) two popular refrigerant replacement candidates with a GWP less than 750, R-32 and R-454B; both have system performance equal to or better than R-410A; (2) the lower-GWP refrigerant options with a GWP below 300 all underperform compared to R-410A; however, heat exchanger optimization may improve system performance; (3) using an ECM instead of a PSC evaporator blower motor increased system seasonal energy efficiency ratio (SEER) performance ~8% for all refrigerants evaluated

RECENT MODALITIES IN DRUG DELIVERY VIA INHALATION THERAPY – AN ADVANCED TREATMENT STRATEGY FOR PULMONARY CARCINOMA

The potential benefit of nanoparticles (NPs) as a colloidal delivery system for pharmaceutical relevance has earned substantial concern in the past decades. Fatality rate due to cancer sustained to hike; advances in nanotechnology have quite become a trenchant approach for enhancing effective drug targeting to cancer tissues by circumventing all the imperfections of traditional chemotherapy. Inhalation drug delivery directly targeting the lungs through respiratory tract is a rapidly maturing field of research and most recently explored approaches for both local and systemic therapy. With the recent advances in synthesis and manipulation of nanoparticles, inhalation drug delivery has shown great impact on pulmonary practice. Inhalation drug delivery has diverse actions over traditional chemotherapy including a) non-invasive b) avoiding first pass metabolism and systemic toxicity c) minimized frequent dosing and d) target delivery of drug to the lung epithelium thereby enhancing local drug concentrations. Dry powder inhalers, meter dose inhalers and nebulizers are some few efficient methods to deliver therapeutic agents directly targeting to the lungs. The ultimatum of inhalation therapy is to generate particles with an ample range of particle sizes. With the recent interest in the development of pulmonary targeted therapy, this review presents how the inhalation drug delivery overcomes conventional chemotherapy and focuses the recent treatment modalities that have been established for pulmonary carcinoma by the route of inhalation as well as discusses the advantages of inhalation drug delivery.Â

A Novel Distributed Scroll Booster Architecture for Supermarket Refrigeration

Today’s supermarket system architectures are being designed to minimize global warming potential (GWP) from both direct and indirect carbon emissions. To achieve this, many supermarkets are primarily employing one of two leading strategies: (1) designing and using systems that require smaller refrigerant charges, such as self-contained, secondary, or distributed systems; and (2) using lower-GWP refrigerants such as CO2 in a transcritical system. While both strategies have proved effective, each approach leaves room for improvement. The purpose of this paper is to introduce a third strategy: utilizing a distributed scroll booster system as an emerging alternative for distributed systems. The distributed scroll booster is configured to leverage A1 (R-134a like), low-pressure refrigerants, which enable several key benefits: - Reduced refrigerant charge - Higher system efficiencies - Ability to use common refrigerants and components with which technicians are familiar - Lower leak rates - Future compatibility with A2L refrigerants such as R-516A and R-1234yf which have lower GWPs when codes and standards are updated This paper will introduce how these benefits are realized through the system’s design. It will cover strategies to manage: -Use of low-pressure refrigerants in the distributed scroll booster -Design flexibility and reliability of the distributed scroll booster -Reducing the strain on compressors through the distributed scroll booste

White spot syndrome virus (WSSV) infection in tiger shrimp Penaeus monodon: A non-lethal histopathological rapid diagnostic method using paraffin and frozen sections

White spot syndrome virus (WSSV) infection was induced in tiger shrimp, Penaeus monodon, under laboratory conditions, and histopathological changes in subcuticular epithelial cells of the eye stalk and pleopod were studied sequentially at different time post-challenge. Routine histological techniques using paraffin embedded tissues, as well as frozen tissues, were used to document WSSV infection. Histological manifestations such as cellular hypertrophy in the subcuticular epithelial cells of the eyestalk and pleopod could be detected as early as 18 h postinfection (p.i.) before the manifestation of clinical signs of the diseas

Simulation Model of an Automatic Commercial Ice Machine

Automatic commercial ice making machines that produce a batch of cube ice at regular intervals are known as “cubersâ€. Such machines are commonly used in food service, food preservation, hotel, and health service industries.  Machines are typically rated for the weight of ice produced over a 24 hour period at ambient air temperatures of 90°F and water inlet temperature of 70°F. These cubers typically utilize an air-cooled, vapor-compression cycle to freeze circulating water flowing over an evaporator grid. Once a sufficient amount ice is formed, a valve switches to enable a harvest mode, where the compressor’s discharge gas is routed into the evaporator, thereby releasing ice into a storage bin. The U.S. Department of Energy has set a target of reducing energy usage by 10 – 15% by 2018.  Engineering models are not publicly available to assist designers in achieving the new energy regulations. This paper presents an engineering simulation model that addresses this need. This model simulates the transient operation of a cuber ice machine based on fundamental principles and generalized correlations. The model calculates time-varying changes in the system properties and aggregates performance results as a function of machine capacity and environmental conditons.  Rapid “what if†analyses can be readily completed, enabling engineers to quickly evaluate the impact of a variety of system design options, including the size of the air-cooled heat exchanger, finned surfaces, air / water flow rate, ambient air and inlet water temperature, compressor capacity and/or efficiency for freeze and harvest cycles, refrigerants, suction/liquid line heat exchanger and thermal expansion valve properties. Simulation results from the model were compared with the experimental data of a fully instrumented, standard 500 lb capacity ice machine, operating under various ambient air and water inlet temperatures. Key aggregate measures of the ice machine’s performance are: (1) cycle time (duration of freeze plus harvest cycles), (2) Energy input per 100 lb of ice, and (3) Energy usage during 24 hours. For these measures, the model’s accuarcy is within 5% for a variety of operating conditions.

Steady-State Modeling of Condensing Units with an Economizer Loop

This paper presents an engineering model that simulates the steady-state operation of air-cooled condensing units. Packaged, air-cooled, condensing units includes a compressor, condensing coil, tubing, and fans, fastened to a base or installed within an enclosure. To increase capacity, modern condensing units are being equipped with a brazed-plate heat exchanger for an economizer loop, configured in either upstream or downstream extraction schemes

The role of pregnancy-associated plasma protein-a level in the first trimester of pregnancy and clinical outcome in an urban referral centre

Background: Estimation of serum PAPP-A levels studied predictability for adverse perinatal outcome. This case control study tries to establish the association between low PAPP-A levels among the pregnant woman and adverse maternal foetal outcome.Methods: This is an case-control study during 2017-2018 in the women delivered at Department of OBG at Mehta Hospitals. Women delivered in the labour room  had a first trimester screening of PAPP-A level were explained, taken informed consent, questionnaire which include detailed antenatal history, mode of delivery and baby data.  Depending upon outcome, the subjects are classified as case group or control group, out of the study sample of 264 subjects, 88 patients who had complications were taken as cases and 176 patients with no complications taken as control were undertaken.Results: Low PAPP-A level (<0.5 MoM) showed high incidence of PIH and preeclampsia, followed by IUGR and Preterm. PAPP-A level >0.5 MoM, normal outcome is more than the adverse outcome. The difference in the PAPP-A levels is statistically significant. In women with low PAPP A level, low birth weight found statistically significant when compared with <0.5 PAPP A level. The sensitivity of PAPP A levels in identifying the complicated outcomes was 17.04%.The specificity was 98.85%. The positive predictive value of predicting the complications was 88.23% and negative predictive value of 70.44%.Conclusions: The low PAPP-A levels confirmed during first trimester of pregnancy is associated with adverse maternal and foetal outcome such as PIH, preeclampsia, preterm, IUGR and LBW

Zn2+ cross-linked sodium alginate-g-allylamine-mannose polymeric carrier of rifampicin for macrophage targeting tuberculosis nanotherapy

Our aim was to evaluate the capacity of polymeric nanoparticles (PNPs) to selectively deliver an antituberculosis drug (rifampicin; RF) to alveolar macrophages. Anionic biodegradable copolymer sodium alginate-g-allylamine-mannose (SA-g-AA-M) was synthesized by atom transfer free radical polymerization and direct coupling of the respective conjugates. The fabrication of RF-loaded Zn2+ ion-cross-linked SA-g-AA-M PNPs was conducted by an O/W emulsion method followed by ionotropic gelation. The structural nature of the RF-loaded SA-g-AA-M PNPs was analyzed by Fourier transform infrared (FT-IR) spectroscopy. Meanwhile, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to illustrate the shape and morphology of the nanoparticles. The PNPs were observed as uniform spheres in the nanometer range (<300 nm), with a low polydispersity index, and excellent performance in terms of drug encapsulation and release ability. The PNPs also showed strong antimicrobial activities against Mycobacterium tuberculosis. Cytotoxicity evaluation in VERO cells by an MTT assay suggested that the PNPs have good biocompatibility. Alveolar macrophage targeting was evaluated via cellular uptake by A549 cells. The cellular uptake results revealed that the Zn2+ concentration of the PNPs increases the intracellular concentration of RF and enhances its antitubercular efficiency. Overall, the results suggest that PNPs could lead to the development of a possible mannose-containing carrier for a macrophage-targeting drug delivery system