Optimizing Transport Carrier Free All-Polymer Solar Cells for Indoor Applications: TCAD Simulation under White LED Illumination

This work inspects the utilization of all-polymer solar cells (APSCs) in indoor applications under LED illumination, with a focus on boosting efficiency through simulation-based design. The study employs a SCAPS TCAD device simulator to investigate the performance of APSCs under white LED illumination at 1000 lux, with a power density of 0.305 mW/cm2. Initially, the simulator is validated against experimental results obtained from a fabricated cell utilizing CD1:PBN-21 as an absorber blend and PEDOT:PSS as a hole transportation layer (HTL), where the initial measured efficiency is 16.75%. The simulation study includes an examination of both inverted and conventional cell structures. In the conventional structure, where no electron transportation layer (ETL) is present, various materials are evaluated for their suitability as the HTL. NiO emerges as the most promising HTL material, demonstrating the potential to achieve an efficiency exceeding 27%. Conversely, in the inverted configuration without an HTL, the study explores different ETL materials to engineer the band alignment at the interface. Among the materials investigated, ZnS emerges as the optimal choice, recording an efficiency of approximately 33%. In order to reveal the efficiency limitations of these devices, the interface and bulk defects are concurrently investigated. The findings of this study underscore the significance of careful material selection and structural design in optimizing the performance of APSCs for indoor applications.

π-π Stacking at the Perovskite/C60 Interface Enables High-Efficiency Wide-Bandgap Perovskite Solar Cells

Interface passivation is a key method for improving the efficiency of perovskite solar cells, and 2D/3D perovskite heterojunction is the mainstream passivation strategy. However, the passivation layer also produces a new interface between 2D perovskite and fullerene (C60), and the properties of this interface have received little attention before. Here, the underlying properties of the 2D perovskite/C60 interface by taking the 2D TEA2PbX4 (TEA = C6H10NS; X = I, Br, Cl) passivator as an example are systematically expounded. It is found that the 2D perovskite preferentially exhibits (002) orientation with the outermost surface featuring an oriented arrangement of TEACl, where the thiophene groups face outward. The outward thiophene groups further form a strong π-π stacking system with C60 molecule, strengthening the interaction force with C60 and facilitating the creation of a superior interface. Based on the vacuum-assisted blade coating, wide-bandgap (WBG, 1.77 eV) perovskite solar cells achieved impressive records of 19.28% (0.09 cm2) and 18.08% (1.0 cm2) inefficiency, respectively. This research not only provides a new understanding of interface processing for future perovskite solar cells but also lays a solid foundation for realizing efficient large-area devices.

Protective role of iron oxide nanocomposites on disease index, and biochemical resistance indicators against Fusarium oxysporum induced-cucumber wilt disease: In vitro, and in vivo studies

Recently nanocomposites have become a super-growth inducers as well as vital antifungal agents, which enhance plant growth and suppress plant diseases. A new strategy regarding the fabrication of humic acid (H) and boron (B) conjugated Fe₂O₃ nanocomposites was performed. Fe₂O₃ NP-B and Fe₂O₃ NP-H were synthesized in the presence of gamma-rays (as a direct reducing agent). Gamma-rays provoked reduction of metal ions due to the liberated reducing electrons, (e^-_aq), in aqueous solutions which can be considered as direct reduction. Antifungal potential against Fusarium oxysporum, the causative agent of wilt disease in cucumber was determined. Disease index percent, metabolic resistance indicators in cucumber plant as response to promotion of systemic resistance (SR) were recorded. Results illustrated that both Fe₂O₃ NPs-B and Fe₂O₃ NPs-H had antifungal activity against F. oxysporum in vitro as well as in vivo. Results revealed that minimum inhibitory concentrations of Fe₂O₃ NPs-B and Fe₂O₃ NPs-H were 0.25 and 0.125 mM, respectively. Application of Fe₂O₃ NPs-B (0.25 mM) and Fe₂O₃ NPs-H (0.125 mM) appeared highly reduced the cucumber wilt disease symptoms incidence caused by F. oxysporum, and recorded disease severity by 83.33%. Fe₂O₃ NPs-B was the best treatment reducing disease indexes by 20.83% and gave highly protection against wilt disease by 75.0% and came next Fe₂O₃ NPs-H which reduced disease indexes by 25% and gave 69.99% protection against disease. Fe₂O₃ NPs-B and Fe₂O₃ NPs-H treatments improved morphological traits, photosynthetic pigments, osmolytes, total phenol and antioxidant enzymes activities in both infected and non-infected plants. The beneficial effects of the Fe₂O₃ NPs-B and Fe₂O₃ NPs-H were extended to increase not only the total phenol, and total soluble protein content but also the activities of peroxidase (POD), and polyphenol oxidase (PPO) enzymes of the healthy and infected cucumber plants in comparison with control.

Boosting the Electrostatic MEMS Converter Output Power by Applying Three Effective Performance-Enhancing Techniques

This current study aims to enhance the electrostatic MEMS converter performance mainly by boosting its output power. Three different techniques are applied to accomplish such performance enhancement. Firstly, the power is boosted by scaling up the technology of the converter CMOS accompanied circuit, the power conditioning, and power controlling circuits, from 0.35 µm to 0.6 µm CMOS technology. As the converter area is in the range of mm², there are no restrictions concerning the scaling up of the accompanied converter CMOS circuits. As a result, the maximum voltage of the system for harvesting energy, V_max, which is the most effective system constraint that greatly affects the converter's output power, increases from 8 V to 30 V. The output power of the designed and simulated converter based on the 0.6 µm technology increases from 2.1 mW to 4.5 mW. Secondly, the converter power increases by optimizing its technological parameters, the converter thickness and the converter finger width and length. Such optimization causes the converter output power to increase from 4.5 mW to 11.2 mW. Finally, the converter structure is optimized to maximize its finger length by using its wasted shuttle mass area which does not contribute to its capacitances and output power. The proposed structure increases the converter output power from 11.2 mW to 14.29 mW. Thus, the three applied performance enhancement techniques boosted the converter output power by 12.19 mW, which is a considerable enhancement in the converter performance. All simulations are carried out using COMSOL Multiphysics 5.4.

Device Modeling of Efficient PBDB-T:PZT-Based All-Polymer Solar Cell: Role of Band Alignment

In this study, we present some design suggestions for all-polymer solar cells by utilizing device simulation. The polymer solar cell under investigation is formed by a photoactive film of a blend comprising PBDB-T as a polymer donor and PZT as a polymerized small molecule acceptor. The initial cell is based on a fabricated cell whose structure is ITO/PEDOT:PSS/PBDB-T:PZT/PFN-Br/Ag, which has a power conversion efficiency (PCE) of about 14.9%. A calibration procedure is then performed by comparing the simulation results with experimental data to confirm the simulation models, and the material parameters, implemented in the SCAPS (Solar Cell Capacitance Simulator) simulator. To boost the open circuit voltage, we investigate a group of hole transport layer (HTL) materials. An HTL of CuI or P3HT, that may replace the PEDOT:PSS, results in a PCE of higher than 20%. However, this enhanced efficiency results in a minor S-shape curve in the current density-voltage (J-V) characteristic. So, to suppress the possibility of the appearance of an S-curve, we propose a double HTL structure, for which the simulation shows a higher PCE with a suppressed kink phenomenon due to the proper band alignment. Moreover, the designed cell is investigated when subjected to a low light intensity, and the cell shows a good performance, signifying the cell's suitability for indoor applications. The results of this simulation study can add to the potential development of highly efficient all-polymer solar cells.

Full Optoelectronic Simulation of Lead-Free Perovskite/Organic Tandem Solar Cells

Organic and perovskite semiconductor materials are considered an interesting combination thanks to their similar processing technologies and band gap tunability. Here, we present the design and analysis of perovskite/organic tandem solar cells (TSCs) by using a full optoelectronic simulator (SETFOS). A wide band gap lead-free ASnI₂Br perovskite top subcell is utilized in conjunction with a narrow band gap DPPEZnP-TBO:PC61BM heterojunction organic bottom subcell to form the tandem configuration. The top and bottom cells were designed according to previous experimental work keeping the same materials and physical parameters. The calibration of the two cells regarding simulation and experimental data shows very good agreement, implying the validation of the simulation process. Accordingly, the two cells are combined to develop a 2T tandem cell. Further, upon optimizing the thickness of the front and rear subcells, a current matching condition is satisfied for which the proposed perovskite/organic TSC achieves an efficiency of 13.32%, J_sc of 13.74 mA/cm², and V_oc of 1.486 V. On the other hand, when optimizing the tandem by utilizing full optoelectronic simulation, the tandem shows a higher efficiency of about 14%, although it achieves a decreased J_sc of 12.27 mA/cm². The study shows that the efficiency can be further improved when concurrently optimizing the various tandem layers by global optimization routines. Furthermore, the impact of defects is demonstrated to highlight other possible routes to improve efficiency. The current simulation study can provide a physical understanding and potential directions for further efficiency improvement for lead-free perovskite/organic TSC.

Cyanobacteria-Mediated Immune Responses in Pepper Plants against Fusarium Wilt

Research in plant pathology has increasingly focused on developing environmentally friendly, effective strategies for controlling plant diseases. Cyanobacteria, including Desmonostoc muscorum, Anabaena oryzae, and Arthrospiraplatensis, were applied to Capsicum annuum L. to induce immunity against Fusarium wilt. Soil irrigation and foliar shoots (FS) application were used in this investigation. The disease symptoms, disease index, osmotic contents, total phenol, Malondialdehyde (MDA), hydrogen peroxide (H₂O₂), antioxidant enzymes (activity and isozymes), endogenous hormone content, and response to stimulation of defense resistance in infected plants were assessed. Results demonstrated that using all cyanobacterial aqueous extracts significantly reduced the risk of infection with Fusarium oxysporum. One of the most effective ways to combat the disease was through foliar spraying with Arthrospira platensis, Desmonostoc muscorum, and Anabaena oryzae (which provided 95, 90, and 69% protection percent, respectively). All metabolic resistance indices increased significantly following the application of the cyanobacterial aqueous extracts. Growth, metabolic characteristics, and phenols increased due to the application of cyanobacteria. Polyphenol oxidase (PPO) and peroxidase (POD) expressions improved in response to cyanobacteria application. Furthermore, treatment by cyanobacteria enhanced salicylic acid (SA) and Indole-3-Acetic Acid (IAA) in the infected plants while decreasing Abscisic acid (ABA). The infected pepper plant recovered from Fusarium wilt because cyanobacterial extract contained many biologically active compounds. The application of cyanobacteria through foliar spraying seems to be an effective approach to relieve the toxic influences of F. oxysporum on infected pepper plants as green and alternative therapeutic nutrients of chemical fungicides.

Validation and Evaluation of a Behavioral Circuit Model of an Enhanced Electrostatic MEMS Converter

In this current study, the validation and evaluation of a behavioral circuit model of electrostatic MEMS converters are presented. The main objective of such a model is to accurately find the converter behavior through the proper choice of its circuit elements. In this regard, the model enables the implementation of the electrostatic MEMS converter using commercially available off-shelf circuit elements. Thus, the overall vibration energy harvesting system can be implemented and tested without the need for fabricating the converter. As a result, the converter performance can be verified and evaluated before its fabrication which saves the expenses of fabricating trailed prototypes. To test the model, we apply it to an enhanced converter in which the conventional electrostatic MEMS converter is modified by depositing the tantalum pentoxide, Ta2O5, a high dielectric constant material, on its fingers’ sidewalls. Such a deposition technique causes an appreciable increase in the overall converter capacitance and, in turn, the output power, which is boosted from the range of µw to the range of mW. Next, the converter behavioral circuit model, which is based on representing its capacitances variations with respect to the input displacement, x caused by the vibration signal, C–x curve, is built up. The model is qualitatively validated and quantitatively evaluated. The enhanced converter performance is investigated through the interaction of its model with the power conditioning circuit. From the simulation results, it is revealed that the converter behavioral circuit model accurately accomplishes the vibration energy conversion operation. As a result, the specification of the required controlling pulses for the converter operation is accurately determined. Finally, the model accuracy is validated by calibrating its performance with a traditionally simulated and fabricated electrostatic MEMS converter.

Bandwidth Broadening of Piezoelectric Energy Harvesters Using Arrays of a Proposed Piezoelectric Cantilever Structure

One of the most important challenges in the design of the piezoelectric energy harvester is its narrow bandwidth. Most of the input vibration sources are exposed to frequency variation during their operation. The piezoelectric energy harvester’s narrow bandwidth makes it difficult for the harvester to track the variations of the input vibration source frequency. Thus, the harvester’s output power and overall performance is expected to decline from the designed value. This current study aims to solve the problem of the piezoelectric energy harvester’s narrow bandwidth. The main objective is to achieve bandwidth broadening which is carried out by segmenting the piezoelectric material of the energy harvester into n segments; where n could be more than one. Three arrays with two, four, and six beams are shaped with two piezoelectric segments. The effect of changing the length of the piezoelectric material segment on the resonant frequency, output power, and bandwidth, as well as the frequency response is investigated. The proposed piezoelectric energy harvesters were implemented utilizing a finite element method (FEM) simulation in a MATLAB environment. The results show that increasing the number of array beams increases the output power and bandwidth. For the three-beam arrays, at n equals 2, 6 mW output power and a 9 Hz bandwidth were obtained. Moreover, the bandwidth of such arrays covered around 5% deviation from its resonant frequency. All structures were designed to operate as a steel wheel safety sensor which could be used in train tracks.

In vitro assessment of dual (antiviral and antitumor) activity of a novel lectin produced by the newly cyanobacterium isolate, Oscillatoria acuminate MHM-632 MK014210.1

A novel lectin was purified from newly cyanobacterium isolate, Oscillatoria acuminate MHM-632 MK014210.1 using affinity chromatography with a molecular weight of 120 kDa under native-PAGE and 30 kDa on reducing-PAGE, represented tetramer nature of this lectin. Oscillatorial lectin showed stability at 60 °C for 30 min, pH-dependent, with the highest activities over the pH range of 6-8, and required zinc ions to express its full activity. Oscillatorial lectin is a glycan-binding protein with a neutral carbohydrate content of 7.0% as evaluated by the phenol-sulfuric acid method. Polyols and α- glycosides polymer of mannose sugar or sugars alcohol were completely inhibited oscillatorial lectin with MIC of 0.195 mM, while β-glycosides sugars did not show any inhibition effect. The oscillatorial lectin has anti-proliferative activity against Huh-7 and MCF-7 cancer cells and inhibited their proliferation with EC₅₀ values of 106.75 µg/ml and 254.14 µg/ml, respectively. Besides the anticancer effect, oscillatorial lectin also has potent antiviral activity against HSV-1 in a dose-dependent manner via virions neutralization and inhibition of viral replication with IC₅₀ values of 90.95 ng/ml and 131.3 ng/ml, respectively. The unique carbohydrate affinity of oscillatorial lectin provides insight into its use as a promising candidate in many biotechnological applications, like fighting viral infection and combating cancer disease.Communicated by Ramaswamy H. Sarma.

The use of cyanobacterial metabolites as natural medical and biotechnological tools: review article

Cyanobacteria are photosynthetic, Gram-negative bacteria that are considered one of the most morphologically diverse groups of prokaryotes with a chief role in the global nutrient cycle as they fixed gaseous carbon dioxide and nitrogen to organic materials. Cyanobacteria have significant adaptability to survive in harsh conditions due to they have different metabolic pathways with unique compounds, effective defensive mechanisms, and wide distribution in different habitats. Besides, they are successfully used to face different challenges in several fields, including industry, aquaculture, agriculture, food, dairy products, pollution control, bioenergy, and pharmaceutics. Analysis of 680 publications revealed that nearly 1630 cyanobacterial molecules belong to different families have a wide range of applications in several fields, including cosmetology, agriculture, pharmacology (immunosuppressant, anticancer, antibacterial, antiprotozoal, antifungal, anti-inflammatory, antimalarial, anticoagulant, anti-tuberculosis, antitumor, and antiviral activities) and food industry. In this review, we nearly mentioned 92 examples of cyanobacterial molecules that are considered the most relevant effects related to anti-inflammatory, antioxidant, antimicrobial, antiviral, and anticancer activities as well as their roles that can be used in various biotechnological fields. These cyanobacterial products might be promising candidates for fighting various diseases and can be used in managing viral and microbial infections.Communicated by Ramaswamy H. Sarma.

Substitution at Phenyl Rings of Chalcone and Schiff Base Moieties Accounts for their Antiproliferative Activity

BACKGROUND

In a continuous combat against cancer, which is one of the leading causes of mortality now, chalcone and Schiff bases moieties have been incorporated and their antiproliferative activities and associated mechanisms against liver (HepG2) and breast (MCF-7) cell lines in addition to normal fibroblasts (WI-38) have been examined.

METHODS

Derivatives 4 and 5 of Schiff bases only and chalcone derivatives of Schiff bases 1 and 2 were devoid of any antiproliferative activity. All three compounds (3, 6, and 7) with significant antiproliferative activity were selective and caused no growth inhibition in normal fibroblasts. Derivative 3 was a chalcone only with IC50 of ~20 µM and has a very interesting signature where it enhanced apoptosis in HepG2 by stimulating the expression of downstream execution caspase 3 without affecting neither p53 nor initiator caspase 9. In spite of the structural similarity between compounds 6 and 7, compound 6 discerned itself with a unique IC50 of ~ 10 µM.

RESULTS

The antiproliferative activity of derivative 6 could be attributed to its unique capability of formation of free radicals such as phenoxide radicals which arrested the cell cycle through enhancing the expression of p53 and induced apoptosis by induction of both caspases 9 and 3. It was the only investigated derivative that inhibited the tyrosine kinase activity by 89%.

CONCLUSIONS

The antiproliferative activity of the compounds under investigation considerably depended on the nature of the substituent at position 4 in phenyl rings of both chalcone and Schiff base fragments. Derivative 6 with electron withdrawing chlorine substitution on the phenyl ring of Schiff base fragment and an electron donating methoxy group on the phenyl ring of chalcone fragment was the most active member.

Traumatic renal injury: Five-year experience at a major trauma centre in South Africa

BACKGROUND

This study is intended to assess the current optimal management of traumatic renal injuries (TRIs), with a focus on high-grade and penetrating injuries.

METHODS

The Pietermaritzburg Metropolitan Trauma Service registry was interrogated retrospectively for patients managed for TRI between 1 January 2012 and 31 December 2016.

RESULTS

Of 13,315 inured patients treated by the PMTS, 223 (1.7%) had TRIs with an incidence of 1.5 per 100,000 population per year. The majority were males between 20 and 39 years of age. The distribution of mechanism of injury was 56.1% (n = 125) blunt and 43.9% (n = 98) penetrating trauma with no association between mechanism and grade of injury. Penetrating trauma was associated with hollow viscus and diaphragm injuries and blunt trauma with solid organ injuries. A total of 118 patients (52.9%) were managed non-operatively, 60 (26.9%) were not explored at operation, 27 (12.1%) underwent initial nephrectomy and 8 (3.6%) underwent renorraphy. Low-grade injuries (AAST I and II) and high-grade injuries (AAST III-V) were managed without renal intervention (non-operatively or not explored at laparotomy for associated injuries) in 88.7% (n = 87) and 72.0% (n = 91) of cases respectively. Blunt and penetrating injuries were managed without renal intervention in 87.9% (n = 109) and 70% (n = 69) of cases respectively. The initial nephrectomy rate was 1% (n = 1) and 20.6% (n = 26) for low- and high-grade injuries respectively, and 6.5% (n = 8) and 19% (n = 19) for blunt and penetrating injuries respectively. High grade (AAST III-V) injury (OR 14.94; 95% CI 3.36 - 66.34; p<0.001), penetrating mechanism (OR 4.99; 95% CI 1.98 - 12.52; p = 0.001) and metabolic acidosis (OR 2.73; 95% CI 1.04 - 7.20; p = 0.042) were significant risk factors for nephrectomy. Four patients (1.8%) underwent ureteral stent insertion and 2 (0.9%) underwent embolisation. The failure rate of initial non-operative management was 1.1%. The mortality rate was 8.1% (n = 18), but no patients with solitary renal injuries died.

CONCLUSION

Even in high-grade injuries and penetrating trauma, the majority of patients with TRI can be managed non-operatively or with the assistance of endourological or endovascular techniques, with good outcomes. Risk factors for nephrectomy include the presence of high-grade injuries, penetrating trauma and metabolic acidosis on presentation.

Dissolution enhancement of gliclazide using ultrasound waves and stabilizers in liquid anti-solvent precipitation

The absorption rate of gliclazide is slow and variable among subjects probably due to poor dissolution from the dosage form. The objective of this study was to enhance the dissolution rate of gliclazide by reducing the particle size. Gliclazide was precipitated from an acetone solution by adding an antisolvent (water) containing stabilizers. A combination of jets (flow rate of 20 ml/min), ultrasound, HPMC 4000, and sodium dodecyl sulfate was used to control particle size and particle size distribution. The effects of concentration of stabilizers, initial drug concentration in solution, time of insonation, antisolvent-to-solvent ratio, and ultrasound power on particle size and particle size distribution were studied. Precipitated drug particles were characterized by laser diffraction particle size analysis, SEM, FTIR spectroscopy, DSC, powder x-ray diffraction and in-vitro dissolution. With increasing almost all the studied parameters, the particle size of gliclazide initially decreased, exhibited a minimum, and then increased. Drug particles of glicazide with a mean particle size of 1.56 ± 0.09 μm and a narrow size distribution (d10/d50/d90 = 0.67/1.67/2.26) were precipitated as compared to unprocessed gliclazide with a mean particle size of 10.67 ± 0.04 μm and a wide size distribution (d10/ds50/d90 = 4.53/9.88/18.03). SEM images indicated changes in the particle morphology. Powder x-ray diffraction patterns and DSC curves indicated no changes in the chemical properties but only decrease in crystallinity and/or particle size. The dissolution rate was enhanced 2.55-fold. In conclusion, drug particles with small size and narrow size distribution were precipitated by selecting favorable process conditions, and dissolution was enhanced several folds.

Synthesis, antibacterial, and antiviral evaluation of new heterocycles containing the pyridine moiety

A facile one-pot four-component reaction was utilized to construct 2-oxo-1,2-dihydropyridine-3-carbonitrile as a scaffold for the synthesis of many fused heterocyclic systems, namely, furopyridine, pyridothiadiazepinthione, and pyridotriazine, as well as non-fused heterocyclic systems such as phthalazin-2(1H)-ylnicotinonitrile, pyridin-2-yl-1H-pyrazole, and pyrazol-1-ylnicotino-nitrile,1-(3-cyanopyridin-2-yl)-1H-pyrazole. The new compounds were evaluated as antimicrobial and antiviral agents.

Formulation and release behavior of diclofenac sodium in Compritol 888 matrix beads encapsulated in alginate

Sustained-release polymer beads containing diclofenac sodium (DNa) dispersed in Compritol 888 and encapsulated in calcium alginate shell were prepared utilizing 2(3) factorial design. The effect of sodium alginate concentration, drug: Compritol 888 weight ratio and CaCl2 concentration on drug content (%), time for 50% and 80% of the drug to be released, and mean dissolution time (MDT) were evaluated with analysis of variance (ANOVA). An increase in the level of all these factors caused retardation in the release, and t50%, t80%, and MDT were increased. The drug release was dependent on the pH of the release media. A formula that gives a release comparable to commercial products was prepared.

Dissolution behaviour of sustained release formulations of indomethacin with Eudragit RS

This study investigates the kinetics of the release of indomethacin from Eudragit RS polymer. It involved the study of the dissolution behaviour of indomethacin from different combinations of the drug in a solid dispersion form, granules and physical mixtures. It was evident that Eudragit RS had a retardation effect on the release of indomethacin, this effect was dependent on the amount of Eudragit included. Inclusion of sodium lauryl sulphate (SLS) in the solid dispersion, granules and physical mixtures modified the release and made it comparable to the release from Indocid retard capsules. The kinetics of the release process was found to be best described by the Higuchi square root of time equation and the first order equation indicating that the release process is diffusion controlled and dependent on the initial drug concentration. The retarding effect Eudragit had on the release of indomethacin was attributed to the possible interaction of the ammonium groups of the polymer with the carboxylate anion of indomethacin and to the inclusion of the drug within the inert insoluble polymer matrix.

Dissolution kinetics of glibenclamide glass

This work examines the dissolution kinetics of glibenclamide crystalline state, form I, and glibenclamide glassy state, form II. This required determination of the pH-solubility profiles of the two forms, dissolution at different stirring rates, temperatures, and pHs. It was found that form II exhibited higher solubility and dissolution rate at all the studied pHs. However, a significant increase in dissolution and solubility of form II was noted at pH 6. Dissolution studies at different stirring rates confirmed that the dissolution process is diffusion controlled, zero order in nature and adheres to the Noyes and Whitney and Levich equations. Dissolution studies at different temperatures enabled calculation of the heat of dissolution, Ea, of both forms. Ea for form I and form II was found to be almost identical. Storing of form II for one week at different temperatures resulted in the partial transformation of form II to form I as indicated from dissolution studies. The extent of transformation and hence reduction in dissolution rate increased with the increase in storage temperature.

Bioequivalence study of two capsule formulations of omeprazole

Bioequivalency of Omeraz, a test-product of Arab Pharmaceutical Manufacturing Company (Jordan) and Losec, a reference product by Astra (Sweden), was evaluated by a randomised crossover study on 22 healthy male volunteers. Serum concentrations of omeprazole were measured by an HPLC assay. There were no statistically significant differences between the two products in terms of serum profile and pharmacokinetic parameters including AUC, Cmax, Tlag, Tmax, MRT, Ke and T1/2. The AUC ratios (Omeraz/Losec) for 24 hours and for infinity were respectively 1.02 with a 90% C.L. of 0.88-1.16 and 1.00 with a 90% C.L. of 0.88-1.14. The two products may be considered as bioequivalent in terms of the extent of absorption as indicated by the AUC ratios. However, the confidence limits of Cmax fall outside the FDA accepted range.

Bioequivalence of two oral dosage forms prepared from different polymorphic modifications of tenoxicam

The bioavailability of two pharmaceutical dosage forms formulated using different polymorphs of tenoxicam were compared. Serum levels of TNX were analysed using high performance liquid chromatography. The pharmacokinetic parameters were estimated following the oral administration of a single dose (20 mg) of the drug as two different polymorphs to 12 healthy volunteers. The differences between formulations were statistically insignificant.

High performance liquid chromatographic analysis of tetroxoprim and sulphadiazine in serum and urine

Quantitative determination of tetroxoprim and sulphadiazine in serum and urine was performed using reversed phase high performance liquid chromatography. Protein precipitation using 10% perchloric acid was utilized for purification of serum samples while urine samples were diluted prior to analysis. The mobile phase consisted of triethylammonium acetate buffer (85%), acetonitrile (12%) and methanol (3%), with a final pH of 4.2. The eluent was monitored at 280 nm. Benzoic acid was used as an internal standard. Standardization, validation and application of the method is described.

Microbial contamination and preservation efficacy of cough preparations

Cough syrups, manufactured by four different Jordanian pharmaceutical companies, were examined for microbial contents and efficacy of preservation from fungal and bacterial contamination. Five per cent of the tested samples were found to be contaminated by Candida albicans and 30% of the products examined did not comply with the pharmacopoeial requirements for optimal preservation from fungal contamination. All the products tested were free from bacteria and were efficiently preserved against accidental bacterial contamination.

High performance liquid chromatographic analysis of caffeine concentrations in plasma and saliva

A rapid high performance liquid chromatographic (HPLC) method for the analysis of caffeine in plasma and saliva is described. Samples of saliva and plasma were purified using zinc sulphate solution as protein precipitant. The supernatant was injected directly onto the column. The mobile phase consisted of ammonium acetate buffer:acetonitrile:methanol (82:15:3, v/v). Measurements were carried out at 254 nm. Acetanilide was used as the internal standard and analysis was completed in 10 min. No interference from endogenous components or other methylxanthines was observed. The coefficients of variation for within day and between day analysis for both saliva and plasma were less than 7.66%. Samples were collected from 20 volunteers. The correlation coefficient between plasma and saliva caffeine concentrations was found to be 0.98.