Integrated liquid-crystal-based variable-tap devices for visible-light amplitude modulation.

In this Letter, we propose and experimentally demonstrate the first, to our knowledge, integrated liquid-crystal-based (LC-based) variable-tap devices for visible-light amplitude modulation. These devices leverage the birefringence of LC medium to actively tune the coupling coefficient between two waveguides. First, we develop the device structure, theory of operation, and design procedure. Next, we summarize the fabrication and LC packaging procedure for these devices. Finally, we experimentally demonstrate amplitude modulation with 15.4-dB tap-port extinction within ±3.1 V for a 14-µm-long device at a 637-nm operating wavelength. These small-form-factor variable-tap devices provide a compact and low-power solution to integrated visible-light amplitude modulation and will enable future high-density integrated visible-light systems.

Liquid-crystal-based visible-light integrated optical phased arrays and application to underwater communications.

In this Letter, we present the first, to the best of our knowledge, liquid-crystal-based integrated optical phased arrays (OPAs) that enable visible-light beam forming and steering. A cascaded OPA architecture is developed and experimentally shown to emit a beam in the far field at a 632.8-nm wavelength with a power full width at half maximum of 0.4°×1.6° and 7.2° beam-steering range within ±3.4 V. Furthermore, we show the first visible-light integrated-OPA-based free-space-optical-communications transmitter and use it to demonstrate the first integrated-OPA-based underwater-wireless-optical-communications link. We experimentally demonstrate a 1-Gbps on-off-keying link through water and an electronically-switchable point-to-multipoint link with channel selectivity greater than 19 dB through a water-filled tank.

Roflumilast ameliorates diabetic nephropathy in rats through down-regulation of JAK/STAT signaling pathway.

Roflumilast is a potent selective inhibitor of the phosphodiesterase-4 enzyme which greatly manifest an anti-inflammatory activity in chronic obstructive pulmonary patients. Inflammation is a prominent factor in the prevalence of diabetic nephropathy, one of the most prevalent microvascular complications of Diabetes Mellitus. The present study was undertaken to assess the potential role of roflumilast in diabetic nephropathy. The model was developed by feeding a high-fat diet for four weeks and following streptozotocin (30 mg/kg) injection intraperitoneally. The rats with > 13.8 mmol/L blood glucose were treated with roflumilast (0.25, 0.5, 1 mg/kg) and standard metformin (100 mg/kg) orally once a day for eight weeks. Roflumilast (1 mg/kg) remarkably improved renal damage, indicated by an increase in 16% albumin, a decrease in 5% serum creatinine, 12% BUN, 19% HbA1c, and 34% blood glucose. It also significantly improves the oxidative stress levels, which was indicated by a decrease in 18% MDA level and an increase in GSH, SOD, and catalase by 6%, 4%, and 5%, respectively. In addition, Roflumilast (1 mg/kg) decreased the HOMA-IR index by 28% and increased the pancreatic ß-cells functioning by 30%. Moreover, significant improvement in histopathological abnormalities were observed in roflumilast treatment groups. Roflumilast treatment was shown to down-regulate the gene expressions of TNF-α (2.1-fold), NF-kB (2.3-fold), MCP-1 (2.5-fold), fibronectin (2.7-fold), collagen IV (2.7-fold), STAT 1(1.06-fold), and STAT 3 (1.20-fold) and upregulated the expression of the Nrf2 (1.43-fold) gene. Roflumilast manifested a potential role in diabetic nephropathy as a renoprotective agent. Roflumilast effectively down-regulates the JAK/STAT pathway and restores renal functions.

Roflumilast alleviates adenine-induced chronic kidney disease by regulating inflammatory biomarkers.

The present investigation was carried out to explore the role of roflumilast, a PDE4 inhibitor, as a potential treatment option for chronic kidney disease. Forty-six male Wistar rats were divided into five groups: Control, Disease control (50 mg/kg Adenine p.o.), Adenine + Roflumilast (0.5, 1 and 1.5 mg/kg, p.o.). Various urinary and serum biomarkers, antioxidant status, histopathology, and protein expression of inflammatory markers were measured to investigate the effects of roflumilast on kidney functions. Adenine was found to elevate the levels of serum creatinine, urea, uric acid, sodium, potassium, chloride, magnesium, and phosphorus and reduce the level of serum calcium. Further, adenine significantly increased the serum TGF-ß levels and reduced the anti-oxidant indices. Significant elevation was observed in protein expression of IL-1ß, TNF-α, MCP-1, ICAM-1, and Fibronectin. Histopathologically, adenine caused thickening of the glomerular basement membrane, inflammatory cells infiltration, atrophy, and glomeruli deterioration. However, Roflumilast administration (1 mg/kg) remarkably decrease serum creatinine, urea, uric acid, sodium, potassium, chloride, magnesium, phosphorus by 61%, 40%, 44%, 41%, 49%, 58%, 59% and 42% respectively, and increase in calcium by 158%. Moreover, Roflumilast (1 mg/kg) significantly reduced serum TGF-ß levels by 50% and elevated anti-oxidant indices by 257%, 112%, and 60%, respectively. The protein expression was significantly reduced by 5.5-fold, 7-fold, 5.7-fold, 6.2-fold, and 5.1-fold individually. Roflumilast noticeably improved the structure of glomeruli, tubules, and cellular functioning. The study confirmed that Roflumilast has the potential to ameliorate renal injury by reducing and regulating inflammatory responses.

SPP1 and UMOD gene variants are synergistically associated with risk of renal stone disease.

OBJECTIVE: Calcium and oxalate are the most abundant metabolites present in the stone matrix. The SPP1 and UMOD gene has specific expression in kidneys and are involved in various stages of stone formation. Therefore, genetic variants in the SPP1 and UMOD genes may enhance the development of renal stone disease. This study has been designed to understand the association of genetic variants of SPP1 and UMOD genes with renal stone disease. MATERIALS AND METHOD: A prospective study has been carried out, including 150 renal stone disease patients and 150 healthy individuals. Biochemical parameters were performed, including serum calcium levels, creatinine, parathyroid hormone, and 24-Hour urine metabolites. The genotyping of SPP1 (rs1126616) and UMOD (rs4293393) gene variants were performed using a customized TaqMan probe. T-test was used for continuous biochemical data analysis. The Chi-square test has been applied to assess the risk of a particular genotype associated with renal stone disease. In addition, correlation analysis for biochemical parameters and genetic variants with the renal stone disease has been performed using Shapley additive explanations (SHAP) values calculated with the help of the pycaret library. RESULT: Renal stone patients had significantly higher levels of parathyroid hormone (93.37 ± 52.78 pg/ml vs 64.67 ± 31.50 pg/ml, P=<0.0001), serum creatinine (0.94 ± 0.38 mg/dl vs 0.77 ± 0.17 mg/dl, P=<0.0001) and 24hr urine metabolites in comparison to the healthy controls. Heterozygous (CT) variant of SPP1 and homozygous (GG) variant of UMOD genes were significantly associated with an increased risk of developing the renal stone disease (p = 0.0100, OR = 2.06, 95 %CI = 1.13-3.75; p=<0.0001, OR = 5.773, 95 % CI = 2.03-16.38, respectively). Individuals with hyperparathyroidism and CC (SPP1) and GG (UMOD) genotypes have a high risk (P = 0.0055, OR = 2.75, 95 %CI = 1.35-5.67; P = 0.0129, OR = 10.03, 95 %CI = 1.60-110.40, respectively) of developing a renal stone. In addition, individuals with hypercalciuria and TT genotype of SPP1 (P = 0.0112, OR = 2.92, 95 % CI = 1.33-6.35), AG genotype of UMOD (P=<0.0001, OR = 5.45, 95 %CI = 2.24-13.96) and GG genotype of UMOD (P=<0.0001, OR = 10.02, 95 %CI = 3.53-24.63) have high risk of developing renal stones. Moreover, Individuals with hyperoxaluria and AG + GG (UMOD) genotype have a greater risk (P=<0.0001, OR = 7.35, 95 % CI = 3.83-13.68) of developing a renal stone. The renal stone risk was persistent (P=<0.0002, OR = 2.44, 95 % CI = 1.52-3.86) when analyzed for the synergistic effect of risk genotypes of SPP1 (CT) and UMOD (GG) gene. Further, correlation analysis also confirmed the strong association between genetic variants and renal stone development. CONCLUSION: Genetic variants of the SPP1 and UMOD genes were associated with renal stone disease. In the presence of risk genotype and hyperparathyroidism, hypercalciuria, and hyperoxaluria, the susceptibility to develop the renal stone disease risk gets modulated.

Estimation of Scopoletin from Roots of Argyreia nervosa (Burm. fill.) Bojer Using a Validated HPLC-Fluorescence Method Optimized Using the Design of Experiment Approach.

BACKGROUND: Argyreia nervosa (Burm. Fil.) Bojer., a woody climber, is indicated in Ayurveda to treat debilities of the male reproductive system, diseases of the nervous system, and chronic ulcers. OBJECTIVE: A sensitive analytical method was developed to estimate bioactive scopoletin from methanolic extract prepared from the medicinally active dried roots of Argyreia nervosa (Burm. fil.) Bojer using HPLC equipped with a fluorescence detector. METHODS: Chromatographic separation was achieved using a LunaTM (C18, 250 × 4.6 mm, id: 5 µm) column using an isocratic mobile phase comprising phosphate buffer (pH 3.5)-acetonitrile (80 + 20, by volume) at a flow rate of 1.0 mL/min. The excitation wavelength was 345 nm, and the emission wavelength was 444 nm. The chromatographic parameters were optimized using the design of the experiment approach after determining the combined effects of selected independent variables on area, retention time, and tailing factor (TF) for the peak corresponding to scopoletin, and the experimental design was validated by navigating through the design space. RESULTS: The developed method was found linear in the range 10-140 ng/mL. The results of the studies confirmed the accuracy, precision, and robustness of the developed analytical method. The plant material was found to contain 0.0125 ± 0.0001% w/w scopoletin on a dried weight basis when estimated using the developed method. CONCLUSION: The method was developed using the HPLC-fluoresence detection by adopting the design of experiment approach and simple sample preparation for the estimation of scopoletin from roots of A. nervosa. HIGHLIGHT: This extremely sensitive analytical method with one-step sample preparation has the potential to be adapted for routine QC procedures.

Development and Validation of a Green Stability-Indicating HPTLC Method for Estimation of Curcumin, Gallic Acid, and Ursolic Acid From Polyherbal Formulation Jatyadi Taila.

BACKGROUND: Jatyadi taila (JT) is a well-known Ayurvedic wound-healing product, comprising 16 different medicinally important plants, including Curcuma longa, Terminalia chebula, and Jasminum officinale. OBJECTIVE: The proposed work discusses the development and validation of the green and economical stability-indicating HPTLC method for quantification of the key marker phytoconstituents, curcumin (CUR), gallic acid (GA), and ursolic acid (UA), from JT. METHOD: Quality standard parameters for JT were determined following standard procedures. The marker constituents CUR, GA, and UA were resolved from JT using toluene-ethyl acetate-formic acid (6:2:1, v/v/v) as the mobile phase and subsequently derivatized to estimate UA. The developed plates were subjected to HPTLC-MS analysis. All constituents were subjected to forced degradation to determine the proposed technique's stability-indicating property and the accelerated stability studies of marketed formulation and marker constituents. Greenness evaluation of the method was aided by the AGREE methodology. RESULTS: The Rf values of CUR, GA, and UA were found to be 0.60 and 0.60; 0.27 and 0.28; and 0.74 and 0.77 from reference standard and oil samples respectively, when analyzed at 366 nm, 290 nm, and 366 nm, respectively. HPTLC-MS was carried out to verify the active constituents present in JT. The constituents followed first-order degradation kinetics. The quantity of CUR, GA, and UA in JT was reduced at the end of accelerated stability studies. The developed approach was validated in compliance with the International Conference on Harmonization (ICH) Q2 (R2) guideline. CONCLUSIONS: Among the chosen key markers, GA was highly unstable during forced degradation. JT should be stored at a controlled temperature using more protective packaging material to ensure its quality and efficacy. HIGHLIGHTS: The developed method can be used as a quality control tool for JT as it can be used to determine the stability of the key marker compounds the herbal formulation.

Haplotype of CaSR gene is associated with risk of renal stone disease in West Indian population.

Calcium is the most abundant metabolite involved in the stone matrix. The CaSR gene controls calcium homeostasis, and genetic variation in the CaSR gene could lead to the development of renal stone disease. Therefore, the current study has been designed to assess the association of genetic variants of CaSR gene polymorphisms with renal stone disease. A single-centric prospective study has been carried out on a total of 300 participants (150 cases and 150 controls). Serum levels of calcium, creatinine, parathyroid hormone, and 24 h urine metabolites were measured. Two polymorphisms, rs1801725 and rs1042636, of the CaSR gene, have been genotyped for each participant. T test, binary logistic regression, and Chi-square analysis were used for statistical analysis. Renal stone patients had significantly higher levels of serum parathyroid hormone, creatinine, and 24-h urine metabolites in comparison to the controls. CaSR gene variants, rs1801725 (GG) and rs1042636 (AA), both have shown significant association with renal stone disease. In addition, individuals having specific genotypes along with metabolic abnormalities such as hypercalcemia and hyperparathyroidism are found to be at a higher significant risk of developing the renal stone disease. In the present study, the haplotype of the CaSR gene has shown an association with renal stone disease. Individuals with hyperparathyroidism and hypercalcemia and risk genotype have a higher susceptibility to developing renal stone disease.

Integrated visible-light liquid-crystal-based phase modulators.

In this work, an integrated liquid-crystal-based phase modulator operating at visible wavelengths was developed and experimentally demonstrated. A visible-light silicon-nitride-based 300-mm-wafer foundry platform and a liquid-crystal integration process were developed to leverage the birefringence of liquid crystal to actively tune the effective index of a section of silicon-nitride waveguide and induce a phase shift over its length. The device was experimentally shown to achieve a 41π phase shift within 4.8 Vpp for a 500-µm-long modulator, which means that a 2π phase shifter would need to be only 24.4 µm long. This device is a compact and low-power solution to the challenge of integrated phase modulation in silicon nitride and paves the way for future low-power small-form-factor integrated systems at visible wavelengths.

Beneficial effects of roots of Argyreia nervosa (Brum.f.) Bojer on testosterone biosynthesis in testis and spermatogenesis in Wistar rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Roots of Argyreia nervosa (Burm.f.) Bojer is used traditionally as an aphrodisiac and mentioned in the indigenous system of medicine as spermatogenic. The roots of the plant are also used as bitter, tonic, and alternative. AIM OF THE STUDY: To study the effect of n-butanol fraction (BTF) and ethyl acetate fraction (ETF) of methanol extract prepared from the roots of Argyreia nervosa and scopoletin isolated from ETF on testosterone biosynthesis in testis and spermatogenesis using rats. MATERIALS AND METHODS: The effect of BTF, ETF, and scopoletin on the testosterone biosynthesis was evaluated by determining the alteration in expression of mRNA corresponding to steroidogenic enzymes and concentration of testosterone using TM-3 cell line. The ability of BTF and ETF in altering the level of testicular cholesterol and testosterone along with mRNA expression corresponding to 3ß-Hydroxy-Δ5-steroid dehydrogenase (3ß-HSD) and Acute Steroid Regulatory Protein (StAR) was evaluated using rats as experimental animals. The sperm concentration in the seminal fluid was determined, and histological studies of testicular tissues were also carried out. RESULTS: Test solutions containing BTF, ETF, and scopoletin showed a dose-dependent and statistically significant increase in the testosterone content when incubated with TM-3 cells. The test solutions also increased the fold expression of mRNA corresponding to StAR and 3ß-HSD enzymes from TM-3 cells. BTF and ETF elevated testicular testosterone levels by 3.57 and 3.84-fold as compared to control animals, while the fractions showed 9.04 and 10.41-fold alteration in expression of mRNA corresponding to StAR, respectively. BTF and ETF altered the expression of mRNA corresponding to 3ß-HSD by 13.43 and 15.04-fold in testicular tissues; moreover, they elevated the activity of 3ß-HSD by 7.11 and 7.73 fold, respectively. The animals treated with BTF and ETF showed increased sperm concentration. Histological observations showed that the lumen of seminiferous tubules was densely populated with spermatozoa and Leydig cells were intensely stained. Extract prepared from fruits of Tribulus terrestris Linn and testosterone served as positive controls. CONCLUSION: BTF, ETF, and scopoletin could promote testosterone biosynthesis by elevating mRNA expression corresponding to StAR, 3ß-HSD, and by increasing 3ß-HSD activity in the testicular tissues. Elevated testosterone concentration in testis promoted spermatogenesis. The studies provided the probable mechanism through which the roots of A. nervosa act as spermatogenic.

Aphrodisiac and spermatogenic potential of alkaloidal fraction of Argyreia nervosa (Burm. f.) Bojer roots in male rats.

Roots of Argyreia nervosa (Burm. f.) Bojer are used as aphrodisiac and spermatogenic in the treatment of male infertility. The present studies included in vivo assessment of alkaloidal fraction in male rats on testosterone synthesis in leydig cells. Studies included oral administration of doses of alkaloidal fraction (10, 25 and 50 mg/kg) to rats. Results showed 100% and 146.7% increment in serum testosterone and serum cholesterol at 50 mg/kg dose level, respectively. At the same dose, 135.29% increase in mounting frequency and 357.14% increase in intromission frequency were also observed. Moreover, mount latency and intromission latency were reduced by 32% and 15.88%. Also, there was significant increase in the weight of testes, prostate, seminal vesicle and epididymis. There was 30.26% rise in sperm concentration in treated animals. We conclude that the alkaloidal fraction up-regulated testosterone biosynthesis in leydig cells and it could be responsible for the aphrodisiac and spermatogenic effect.

Quantification of Scopoletin from the Roots of Argyreia Speciosa (Linn. F) Sweet Using HPLC Through the Concept of Design of Experiment.

BACKGROUND: The roots of Argyreia speciosa (Linn. F) Sweet (family: Convolvulaceae) are used in Ayurveda to treat male reproductive and nervous system disorders. OBJECTIVE: Isolation of scopoletin from the roots of Argyreia speciosa, and development and validation of an analytical method using HPLC for the quantification of scopoletin from the root powder of Argyreia speciosa. METHOD: Scopoletin was isolated from chloroform fraction prepared from hydrolyzed methanolic extract and identified using spectral studies. A reverse-phase HPLC-based analytical method was developed and optimized using the Design of Experiment (DoE) approach to estimate scopoletin from the roots of Argyreia speciosa. Scopoletin was separated and quantified using HPLC containing the C18 column and a PDA detector. The optimized mobile phase was methanol: water (pH∼3.2) [25: 75, %v/v]. RESULTS: The Box-Behnken design was used to optimize chromatographic parameters and the extraction procedure. The validation studies showed a linear relationship (r2=0.998) in the range of 1-40 µg/mL. The LOD and LOQ were found to be 0.28 µg/mL and 0.84 µg/mL, respectively, and the recovery values were found to be between 91.94 and 97.86%. The developed analytical method was found to be robust as well. The amount of scopoletin was estimated to be 0.024 ± 0.0016%w/w from dried root powder. CONCLUSION: The recorded chromatogram and amount of scopoletin determined would serve as one of the standardization parameters to access the quality of raw material containing Argyreia speciosa. HIGHLIGHTS: Developed analytical method may be adopted as a part of the standardization procedure for Argyreia speciosa in the quality control laboratory.

Broadband 200-nm second-harmonic generation in silicon in the telecom band.

Silicon is well known for its strong third-order optical nonlinearity, exhibiting efficient supercontinuum and four-wave mixing processes. A strong second-order effect that is naturally inhibited in silicon can also be observed, for example, by electrically breaking the inversion symmetry and quasi-phase matching the pump and the signal. To generate an efficient broadband second-harmonic signal, however, the most promising technique requires matching the group velocities of the pump and the signal. In this work, we utilize dispersion engineering of a silicon waveguide to achieve group velocity matching between the pump and the signal, along with an additional degree of freedom to broaden the second harmonic through the strong third-order nonlinearity. We demonstrate that the strong self-phase modulation and cross-phase modulation in silicon help broaden the second harmonic by 200 nm in the O-band. Furthermore, we show a waveguide design that can be used to generate a second-harmonic signal in the entire near-infrared region. Our work paves the way for various applications, such as efficient and broadband complementary-metal oxide semiconductor based on-chip frequency synthesizers, entangled photon pair generators, and optical parametric oscillators.

Development and Validation of Stability Indicating High-Performance Thin-Layer Chromatographic (HPTLC) Method for Quantification of Asiaticoside from Centella asiatica L. and its Marketed Formulation.

Background: Ayurvedic medicines help in healing disease with fewer undesirable effects in comparison with an allopathic system of medicine to treat central nervous system (CNS) disorders, as the latter is more expensive. Centella asiatica L. is often used in Ayurvedic formulations for the treatment of CNS disorders. Objective: A stability test using an HPTLC method for the estimation of an important marker asiaticoside (ASI) from C. asiatica powder and marketed formulation was developed. Methods: The marker compound ASI from plant powders and marketed formulations were resolved using toluene-ethyl acetate-methanol-glacial acetic acid (2+7+3+1, v/v/v/v) as the mobile phase and then was derivatized. The plant powder and marketed formulation were also subjected to stability studies. Results: The Rf value of ASI was found in range of 0.43-0.47 for the standard ASI, plant powder, and marketed formulation. It was found that the plant powder and formulation exhibited first-order degradation kinetics. Conclusions: The contents of ASI in the formulation (Churna) and its flow characters reduced at the end of the 6 months during an accelerated stability study. The developed method can be used to quantify ASI in the presence of its degradation products. Highlights: The developed method helps in determining batch to batch variation in the content of ASI in herbal formulations.

Integrated visible light phased array system for autostereoscopic image projection.

We demonstrate a chip-scale autostereoscopic image projection system that utilizes a system of multiple integrated visible light optical phased arrays to reconstruct virtual light fields. Each phased array in this system serves as a micro-projector that illuminates the desired virtual object from a different angle. This recreates the virtual object in space with continuous parallax observable by the human visual system. In this work, a static virtual image with horizontal parallax and a viewing angle of 5° was generated with an array of 16 integrated silicon nitride phased arrays with a 635 nm operating wavelength. Each phased array is comprised of 32×32 optical antennas with passively encoded relative phases. The presented device demonstrates the promise of integrated visible light phased array platforms for implementing projection-based autostereoscopic displays in compact chip-scale platforms suitable for mobile devices.

Transmissive silicon photonic dichroic filters with spectrally selective waveguides.

Many optical systems require broadband filters with sharp roll-offs for efficiently splitting or combining light across wide spectra. While free space dichroic filters can provide broadband selectivity, on-chip integration of these high-performance filters is crucial for the scalability of photonic applications in multi-octave interferometry, spectroscopy, and wideband wavelength-division multiplexing. Here we present the theory, design, and experimental characterization of integrated, transmissive, 1 × 2 port dichroic filters using spectrally selective waveguides. Mode evolution through adiabatic transitions in the demonstrated filters allows for single cutoff and flat-top responses with low insertion losses and octave-wide simulated bandwidths. Filters with cutoffs around 1550 and 2100 nm are fabricated on a silicon-on-insulator platform with standard complementary metal-oxide-semiconductor processes. A filter roll-off of 2.82 dB nm-1 is achieved while maintaining ultra-broadband operation. This new class of nanophotonic dichroic filters can lead to new paradigms in on-chip communications, sensing, imaging, optical synthesis, and display applications.

Stability Indicating Reverse Phase HPLC Method for Estimation of Rifampicin and Piperine in Pharmaceutical Dosage Form.

BACKGROUND: High performance liquid chromatography is an integral analytical tool in assessing drug product stability. HPLC methods should be able to separate, detect, and quantify the various drug-related degradants that can form on storage or manufacturing, plus detect any drug-related impurities that may be introduced during synthesis. OBJECTIVE: A simple, economic, selective, precise, and stability-indicating HPLC method has been developed and validated for analysis of Rifampicin (RIFA) and Piperine (PIPE) in bulk drug and in the formulation. METHOD: Reversed-phase chromatography was performed on a C18 column with Buffer (Potassium Dihydrogen Orthophosphate) pH 6.5 and Acetonitrile, 30:70), (%, v/v), as mobile phase at a flow rate of 1 mL min-1. RESULT: The detection was performed at 341 nm and sharp peaks were obtained for RIFA and PIPE at retention time of 3.3 ± 0.01 min and 5.9 ± 0.01 min, respectively. The detection limits were found to be 2.385 ng/ml and 0.107 ng/ml and quantification limits were found to be 7.228ng/ml and 0.325ng/ml for RIFA and PIPE, respectively. The method was validated for accuracy, precision, reproducibility, specificity, robustness, and detection and quantification limits, in accordance with ICH guidelines. CONCLUSION: Stress study was performed on RIFA and PIPE and it was found that these degraded sufficiently in all applied chemical and physical conditions. Thus, the developed RP-HPLC method was found to be suitable for the determination of both the drugs in bulk as well as stability samples of capsule containing various excipients.

Coherent solid-state LIDAR with silicon photonic optical phased arrays.

We present, to the best of our knowledge, the first demonstration of coherent solid-state light detection and ranging (LIDAR) using optical phased arrays in a silicon photonics platform. An integrated transmitting and receiving frequency-modulated continuous-wave circuit was initially developed and tested to confirm on-chip ranging. Simultaneous distance and velocity measurements were performed using triangular frequency modulation. Transmitting and receiving optical phased arrays were added to the system for on-chip beam collimation, and solid-state beam steering and ranging measurements using this system are shown. A cascaded optical phase shifter architecture with multiple groups was used to simplify system control and allow for a compact packaged device. This system was fabricated within a 300 mm wafer CMOS-compatible platform and paves the way for disruptive low-cost and compact LIDAR on-chip technology.

Integrated optical phased arrays for quasi-Bessel-beam generation.

Integrated optical phased arrays for generating quasi-Bessel beams are proposed and experimentally demonstrated in a CMOS-compatible platform. Owing to their elongated central beams, Bessel beams have applications in a range of fields, including multiparticle trapping and laser lithography. In this Letter, continuous Bessel theory is manipulated to formulate the phase and amplitude conditions necessary for generating free-space-propagating Bessel-Gauss beams using on-chip optical phased arrays. Discussion of the effects of select phased array parameters on the generated beam's figures of merit is included. A one-dimensional splitter-tree-based phased array architecture is modified to enable arbitrary passive control of the array's element phase and amplitude distributions. This architecture is used to experimentally demonstrate on-chip quasi-Bessel-beam generation with a ∼14 mm Bessel length and ∼30 µm power full width at half maximum.

Unidirectional waveguide grating antennas with uniform emission for optical phased arrays.

We demonstrate millimeter-scale optical waveguide grating antennas with unidirectional emission for integrated optical phased arrays. Unidirectional emission eliminates the fundamental problem of blind spots in the element factor of a phased array caused by reflections of antenna radiation within the substrate. Over 90% directionality is demonstrated using a design consisting of two silicon nitride layers. Furthermore, the perturbation strength along the antenna is apodized to achieve uniform emission for the first time, to the best of our knowledge, on a millimeter scale. This allows for a high effective aperture and receiving efficiency. The emission profile of the measured 3 mm long antenna has a standard deviation of 8.65% of the mean. These antennas are state of the art and will allow for integrated optical phased arrays with blind-spot-free high transmission output power and high receiving efficiency for LIDAR and free-space communication systems.