Design of uncertain displacement controlled velocity control system for hydraulic actuator.

Displacement-controlled systems have high efficiency and are widely used in industry. Accurate control of the actuator motion in hydraulic systems is usually a necessity in industrial applications such as the motion of control surfaces in fixed-wing airplanes for flight control as well as the aircraft brake systems. To address this need, the current study was conducted with the goal of developing a high-fidelity model to achieve precise control. This work focused on modeling a hydrostatic transmission that is used for controlling a linear actuator velocity. The flow entering the actuator was changed using a variable displacement pump. The study included examining the stability and performance of the open-loop system. Additionally, the study involved the design of the proportional-integral-derivative PID and H∞ controllers, followed by the analysis of the stability and performance of the closed-loop system with both controllers. Furthermore, the multiplicative uncertainty is taken into account and the robustness of the system is verified using controllers PID and H∞. In the current study,Uncertain parameters such as actuator efficiency, pump speed, and viscous friction coefficient were considered and allowed for a ±5% deviation from their stated values. Taking uncertainty into account ensures that the system performs properly even in case where the design parameters vary within the specified range. The system response is compared for the cases of open-loop system, closed-loop system with PID controller, and closed-loop system with H∞ controller. The results demonstrated that the open-loop system remains stable for real-world applications but shows insufficient performance in terms of input tracking and disturbance rejection. The introduction of the PID controller significantly enhanced the system's response to a reference input; however, its disturbance rejection capabilities in terms of overshoot and settling time were still unsatisfactory. The system equipped with the PID controller failed to meet the robustness requirements. Conversely, the utilization of H∞ controllers yielded superior responses and fulfilled the robustness criteria.

Multi-temporal assessment of land surface temperatures as an indicator of land use/cover changes and climate variability in the Develi Basin, Turkey.

Land surface temperature (LST) is an important parameter that reflects land surface processes of water and energy balance and has been used in assessment of land use/cover changes. However, the use of LST in monitoring changes in non-urban areas such as agricultural areas and wetlands is still limited. In this study, we aim to determine the spatial and temporal changes in LST in a semi-arid agricultural basin in Turkey (Develi Basin), where land use/cover and climatic conditions showed considerable variability since 1980s. Irrigated agriculture have expanded in the basin since 1987, after the construction of a large irrigation project. The basin hosts an internationally important wetland, called the Sultan Marshes, affected negatively by irrigation expansion. The study covers a 39-year period from 1984 to 2022. Four Landsat Thematic Mapper (TM) images acquired in 1984, 1987, 2003, and 2007 and two Landsat 8 OLI/TIRS images acquired in 2014 and 2022 were used in the analyses. The land use/cover changes were evaluated based on Normalized Difference Vegetation Index (NDVI). LST was estimated through top-of-atmosphere brightness temperature from thermal bands of Landsat images. Climate variability from 2014 to 2022 was analyzed with statistical methods. The results indicated that Develi Basin faced both spatial and temporal land use/cover changes. The area covered with natural steppe vegetation and water bodies decreased in the basin. In contrast, the sparsely and densely vegetated soil covers, which mostly denote agricultural areas, increased. Changes in LST values were observed from 1984 to 2022 as a result of climatic factors and land use/cover changes. LST changes were variable across different land use/cover types; LST decreased in irrigated areas and increased in lakes that went dry over years. LST changes proved useful for evaluating land use/cover changes and climatic variations in agricultural basins.

Onion (Allium cepa L.) is potentially a good source of important antioxidants.

Six different cultivars of onions available in the Kuwaiti market were analyzed for various physic-chemical properties, such as, moisture content, sugar composition, TBARS as malondialdehyde, total phenolic content, as well as trolox equivalent antioxidant capacity, these cultivars comprised of US onions white, US onions yellow, Indian onions red, Egyptian onions red, New Zealand onions golden and Saudi onions white. Layers from each onion bulb were manually cut and separated into three nearly equal portions, i.e., outer layers, middle layers and the inner layers. The outermost layers of the bulb showed the highest concentration of antioxidant compounds and a distinct decreasing trend was observed towards the innermost layers in all types of onion samples. The onion samples studied showed variations in carbohydrate contents (glucose, fructose and sucrose), which would have important implications in affecting the flavor (sweetness and pungency) and the suitability of these onions for processing. An important observation is about the distribution of antioxidant compounds with the highest contents in the outmost layers of the onions than in their middle and inner layers. Unfortunately, these outer layers are generally discarded by the consumers thus depriving them of the important health-promoting phytochemicals.

Garlic extract increases non-clipped kidney tubular natriuresis and diuresis in the 2-kidney, 1-clip rat model: Significance in hypertension.

BACKGROUND: Angiotensin II (AngII) is a potent modulator of vascular tone and renal clearance function. Raw garlic aqueous extract (RGAE) inhibits angiotensin I converting enzyme (ACE) dipeptidase activity and therefore AngII generation in the 2-kidney, 1-clip rat model (2K-1Cr). OBJECTIVE: This study investigated the effect of RGAE on the non-clipped kidney clearance function and blood pressure (BP) in the 2 K-1Cr. METHOD: 2K-1Cr were anesthetized, cannulated and instrumentalized and the acute effect during the first hour post-administration of a single intravenous dose of RGAE (30mg/100gb.wt/0.3ml) was tested on: 1- The ACE dipeptidase activity estimated from a reduction in the vasopressor action of angiotensin I [(AngI, 200ng/0.2ml): the precursor of AngII] in one group (n=5); 2- The non-clipped (left) kidney (LK) clearance function in a second group (n=6). Similar protocols were carried out on two groups of normal rats (Nr: n=5+n=6). RESULTS: In the 2K-1Cr, RGAE partially, however significantly, decreased the vasopressor action of AngI. Furthermore, RGAE had no effect on systolic BP, mean BP, plasma osmolarity, LK cortical circulation or glomerular filtration rate. Alternatively, RGAE significantly increased LK urine volume, fractional excretion of water, sodium clearance and fractional excretion of sodium; while significantly decreasing heart rate and LK urine osmolarity. CONCLUSIONS: Our findings suggest that a single i.v. dose of RGAE causes ACE dipeptidase inhibition, thus reducing AngII generation and bioavailability in the 2K-1Cr. This action of RGAE enhances the non-clipped kidney clearance of sodium and water by modulating the tubular handling mechanisms.

Garlic Attenuates Plasma and Kidney ACE-1 and AngII Modulations in Early Streptozotocin-Induced Diabetic Rats: Renal Clearance and Blood Pressure Implications.

Raw garlic aqueous extract (GE) has ameliorative actions on the renin-angiotensin system in type-1 diabetes mellitus (DM); however its effects on plasma and kidney angiotensin I converting enzyme type-1 (ACE-1) and angiotensin II (AngII) require further elucidation. This study investigated the effect of GE on plasma and kidney ACE-1 and AngII concentrations and in relation to systemic and renal clearance indicators significant to blood pressure (BP) homeostasis in early streptozotocin- (STZ-) induced type-1 DM. Normal rats (n = 10) received 0.5 mL normal saline (NR/NS), diabetic rats (n = 10) received 0.5 mL NS (DR/NS), and treated diabetic rats (n = 10) received 50 mg/0.1 mL/100 g body weight GE (DR/GE) as daily intraperitoneal injections for 8 weeks. Compared to NR/NS, DR/NS showed a significant increase in plasma ACE-1 and AngII and conversely a decrease in kidney ACE-1 and AngII. These changes were associated with an increase in BP and clearance functions. Alternatively and compared to DR/NS, DR/GE showed normalization or attenuation in plasma and kidney ACE-1 and AngII. These GE induced rectifications were associated with moderation in BP elevation and renal clearance functions. Garlic attenuates modulations in plasma and kidney ACE-1 and AngII, in addition to BP and renal clearance function in type-1 DM.

Garlic decreases liver and kidney receptor for advanced glycation end products expression in experimental diabetes.

The up-regulation of the receptor for advanced glycation end products (RAGE) has been implicated as a major mediator in the development and progression of diabetic nephropathy and hepatic fibrogenesis. The present study was designed to investigate the potential of garlic (Allium sativum L.) to modulate the level of expression of RAGE in renal and hepatic tissues of diabetic rats. Three groups of rats were studied after 8 weeks following diabetes induction: normal, streptozotocin-induced diabetic (control diabetic), and garlic-treated diabetic rats. A polyclonal antibody of proven specificity to RAGE indicated in immunohistochemical assays that RAGE labeling was significantly increased in renal and hepatic tissues of control diabetic rats compared to the normal group. The increased RAGE labeling involved mesangial cells in glomeruli exhibiting signs of mesangial expansion, mesangial nodule formation and glomerulosclerosis. In the liver, a significant up-regulation of RAGE was observed in hepatocytes and bile ducts and vessels in portal tracts. In 2-dimensional Western blots, RAGE expression in both tissues was dominated by heterogeneous charge variants, represented by 46-50kDa isoforms with more basic pIs compared to their counterparts in normal rats. Compared to control diabetic rats, RAGE labeling in the garlic-treated diabetic group was significantly reduced throughout renal and hepatic regions and was marked by the expression of 43-50kDa acidic charge variants comparable to those observed in normal rats. The capacity of garlic to modulate diabetes-induced up-regulation of selective RAGE polymorphic variants may be implicated in attenuating the detrimental consequences of excessive RAGE signaling manifested by diabetes-associated disorders.

Anti-diabetic and anti-oxidant potential of aged garlic extract (AGE) in streptozotocin-induced diabetic rats.

BACKGROUND: Although aged garlic extract (AGE) shares some active components with fresh garlic and in spite of its palatability and milder side effects, the anti-diabetic and related anti-oxidant properties of AGE have not been investigated extensively, and the reported findings are inconsistent. This study investigated the anti-diabetic effects of 3 incremental doses of AGE in streptozotocin (STZ)-induced diabetic rats (fasting blood sugar > 20 mM). METHOD: Diabetic rats were divided into a control diabetic group (CD) and AGE-treated diabetic group (AGE-D). The AGE-D was divided into 3 groups and accordingly treated with AGE i.p. at 100, 300 and 600 mg/kg daily for 8 weeks. A control normal group (CN) was also included for reference. RESULTS: Compared to the CN group, the CD group showed significant loss of body weight (over 50 %); and decreased serum insulin concentration (10 fold) and total anti-oxidant level and catalase activity (45-70 %) in serum, kidney and liver. Conversely, the CD rats had an elevated blood glucose (nearly 4 fold), serum cholesterol (nearly 2 fold) and triglycerides (>2 fold), erythrocyte glycated hemoglobin (GHb, 3 fold) and kidney and liver lipid peroxidation (MDA levels). Treatment with AGE positively reversed the diabetic changes in the targeted parameters to levels significantly lower than those measured in the CD group and the degrees of attenuation were almost dose dependent especially with the two higher doses. CONCLUSION: AGE exhibits a dose-dependent ameliorative action on indicators of diabetes in STZ-induced diabetic rats.

Garlic (Allium sativum) attenuate glomerular glycation in streptozotocin-induced diabetic rats: A possible role of insulin.

OBJECTIVE: This study investigated the effect of fresh garlic aqueous extract on glomerular glycation in streptozotocin-induced diabetic rats. METHOD: Serum insulin and glucose, in addition to renal corpuscles and erythrocyte hemoglobin glycation were determined in normal saline-treated normal rats (NS-NR), normal saline-treated diabetic rats (NS-DR) and garlic-treated diabetic rats (G-DR). RESULTS: Compared to NS-NR, NS-DR showed significant decrease in serum insulin and increase in serum glucose and hemoglobin glycation. NS-DR also showed intense, diffused glomerular periodic acid Schiff activity. Compared to NS-DR, G-DR showed significant increase in serum insulin and decrease in serum glucose and hemoglobin glycation. Furthermore, the G-DR glomerular periodic acid Schiff activity and distribution was almost restored to that observed in NS-NR. CONCLUSION: Garlic may attenuate glomerular glycation in streptozotocin-induced diabetic rats. This effect could be partially mediated via euglycemia induced by revitalization of endogenous insulin.

Garlic (Allium sativum) down-regulates the expression of angiotensin II AT(1) receptor in adrenal and renal tissues of streptozotocin-induced diabetic rats.

The up-regulation of angiotensin II AT1 receptors has been implicated as a major mediator in the development of hypertension and progressive nephropathy in experimental diabetes. In spite of the documented potential of garlic treatments in ameliorating diabetic complications, the possible involvement of the angiotensin II AT1 receptor, as a central target for the anti-diabetic potential of garlic, has not been explored. Three groups of rats were studied after 8 weeks following diabetes induction: normal, streptozotocin-induced diabetic (control diabetic), and garlic-treated diabetic rats. A polyclonal antibody of proven specificity to the AT1 receptor, as verified by western blotting, indicated in immunohistochemical assays that AT1 receptor labeling was significantly increased in adrenal and renal tissues of control diabetic rats compared to the normal group. The increased AT1 receptor labeling involved all cortical zones and medullary chromaffin cells of the adrenal gland. Except for glomerulii, increased AT1 receptor labeling was also evident in proximal convoluted tubules in the renal cortex, and all tubular segments and interstitial cells outlining the vasa recta bundles in the inner stripe of the outer renal medulla. Compared with control diabetic rats, the labeling of the AT1 receptor in the garlic-treated diabetic group was significantly reduced throughout adrenal and renal regions to levels comparable to those observed in normal rats. The capacity of garlic to modulate diabetes-induced AT1 receptor up-regulation may be implicated in reversing the detrimental consequences of excessive Ang II signaling, manifested by the development of hypertension and nephropathy.

Green Tea Attenuates Oxidative Stress and Downregulates the Expression of Angiotensin II AT(1) Receptor in Renal and Hepatic Tissues of Streptozotocin-Induced Diabetic Rats.

This study investigates the potential of green tea to modulate oxidative stress and angiotensin II AT(1) receptor expression in renal and hepatic tissues of diabetic rats. Three groups of rats were studied after 8 weeks following diabetes induction: normal, streptozotocin-induced diabetic (diabetic control), and green-tea-treated diabetic rats. Total antioxidant, catalase, and malondialdehyde levels were assayed by standard procedures. Levels of AT(1) receptor labeling, in renal and hepatic tissues of the three rat groups, were immunohistochemically investigated using an anti-AT(1) receptor antibody. Levels of total antioxidant and catalase were significantly reduced, whereas malondialdehyde levels and AT(1) receptor labeling were significantly increased in renal and hepatic tissues of diabetic control rats compared to normal rats. Compared to diabetic control rats, total antioxidant and catalase levels were significantly increased, whereas malondialdehyde levels and AT(1) receptor labeling in the green-tea-treated diabetic group were significantly reduced throughout hepatic lobules and renal cortical and medullary vascular and tubular segments to levels comparable to those observed in normal rats. The capacity of green tea to modulate diabetes-induced oxidative stress and AT(1) receptor upregulation may be beneficial in opposing the deleterious effects of excessive angiotensin II signaling, manifested by progressive renal and hepatic tissue damage.

Garlic increases antioxidant levels in diabetic and hypertensive rats determined by a modified peroxidase method.

Oxidative damage by free radicals has been implicated in the pathogenesis of vascular disease in diabetes and hypertension. In the present study, the total antioxidant status in diabetic and hypertensive rats before and after treatment with garlic (Allium sativum) was determined. The total serum antioxidants were measured by a modified method reported earlier by Miller and coworkers. The reproducibility of the assay was confirmed by determining standard curves for the known antioxidants: trolox (a stable analog of vitamin E), glutathione and vitamin C with interassay correlation coefficients (R(2), n = 10 in triplicate) of 0.9984, 0.9768 and 0.987, respectively, confirming the reliability and reproducibility of the assay. This assay was then used to determine total serum antioxidant levels of streptozotocin-induced diabetic rats and two-kidney one-clip hypertensive rats both before and after 3 weeks of treatment with an aqueous extract of garlic (500 mg/kg IP daily). The serum antioxidant levels of rats after 3 weeks of treatment were significantly higher (P < .001) than the pretreatment levels in both diabetic and hypertensive rats. The increased serum antioxidant levels were paralleled by a decrease in serum glucose in the garlic-treated diabetic rats and lowered systolic blood pressure in the garlic-treated hypertensive rats. We conclude from our study that (i) total antioxidants can be measured by a simple, reproducible, reliable assay and (ii) the total antioxidant status can be significantly improved by treatment with garlic.

Anti-diabetic and hypolipidaemic properties of ginger (Zingiber officinale) in streptozotocin-induced diabetic rats.

In the present study, the hypoglycaemic potentials of ginger (Zingiber officinale) were studied in rats. An aqueous extract of raw ginger was administered daily (500 mg/kg, intraperitoneally) for a period of 7 weeks to streptozotocin (STZ)-induced diabetic rats. Fasting blood serum was analysed for blood glucose, cholesterol and triacylglycerol levels. The STZ-injected rats exhibited hyperglycaemia accompanied with weight loss, indicating their diabetic condition. At a dose of 500 mg/kg, raw ginger was significantly effective in lowering serum glucose, cholesterol and triacylglycerol levels in the ginger-treated diabetic rats compared with the control diabetic rats. The ginger treatment also resulted in a significant reduction in urine protein levels. In addition, the ginger-treated diabetic rats sustained their initial weights during the treatment period. Moreover, ginger decreased both water intake and urine output in the STZ-induced diabetic rats. The present results indicate that raw ginger possesses hypoglycaemic, hypocholesterolaemic and hypolipidaemic potential. Additionally, raw ginger is effective in reversing the diabetic proteinuria observed in the diabetic rats. Thus, ginger may be of great value in managing the effects of diabetic complications in human subjects.

Nitric oxide mediates the blood-pressure lowering effect of garlic in the rat two-kidney, one-clip model of hypertension.

Garlic reduces blood pressure (BP) in two-kidney, one-clip (2K-1C) rats, and enhances nitric oxide (NO) synthesis in in vivo and in vitro experiments. NO is an important modulator of BP in the 2K-1C model. This study investigated the role of NO in the BP-lowering effect of garlic in the 2K-1C model. BP readings (mm Hg) were obtained from 2K-1C rats in 4 groups treated intraperitoneally for 2 wk with either normal saline (NS), garlic, L-nitroarginine-methylester (L-NAME), or L-NAME+garlic (n=4x5). BP was determined using the tail-cuff method and compared with data of 4 similarly treated groups of normal (unclipped) rats (NRs). The BP readings of NR groups were 120+/-3 mm Hg for the NS-treated group, 120+/-2 mm Hg for the garlic-treated group, 167+/-3 mm Hg for the L-NAME treated group (higher than NS or garlic, P<0.001) and 128+/-5 mm Hg for the garlic+L-NAME-treated group (lower than L-NAME, P<0.001). The BP readings of 2K-1C rat groups were: for the NS group, 169+/-6 mm Hg (higher than NRs, P<0.001); for the garlic group, 116+/-7 mm Hg (lower than NS, P<0.001); for the L-NAME group: 184+/-8 mm Hg (higher than garlic, P<0.001), and for the L-NAME+garlic group: 130+/-6 mm Hg (lower than garlic or NS, P<0.001). The data show that L-NAME increases the BP of both NRs and 2K-1C rats, with the rise more evident in the NRs (39 vs. 9%, respectively). Garlic counteracts the hypertensive effect of L-NAME in NRs as well as 2K-1C rats. We conclude that the BP-lowering effect of garlic in the rat 2K-1C model may be partly mediated through the NO pathway.

Including garlic in the diet may help lower blood glucose, cholesterol, and triglycerides.

Raw and boiled aqueous extracts of garlic (Allium sativum) were administered daily to normal rats both orally and intraperitoneally for 4 wk. The serum levels of glucose, cholesterol, and triglycerides were measured. When the rats were treated with a low dose (50 mg/kg) of raw aqueous extract of garlic, no significant changes in the serum glucose levels were observed compared with the control group. However, there was a significant reduction in the cholesterol level of rats receiving a low dose of garlic (11-14%). Rats receiving garlic orally and intraperitoneally also showed a significant reduction in triglyceride levels (38%). When the rats were treated with a high dose (500 mg/kg) of raw garlic, glucose, cholesterol, and triglyceride levels were significantly affected. When boiled garlic extracts were administered at high concentrations (500 mg/kg), there was no effect on the level of serum glucose. However, a relatively small but significant decrease in the concentration of cholesterol and triglycerides was observed in the serum of the rats receiving boiled garlic. Raw garlic had a profound effect in reducing the glucose, cholesterol, and triglyceride levels, whereas boiled garlic had little effect in controlling these parameters. Therefore because hyperlipidemia is a major etiopathological factor for atherosclerosis, garlic may play an important role in the prevention of atherosclerosis.

Garlic [Allium sativum]: a review of its potential use as an anti-cancer agent.

Garlic [Allium sativum] is among the oldest of all cultivated plants. It has been used as a medicinal agent for thousands of years. It is a remarkable plant, which has multiple beneficial effects such as antimicrobial, antithrombotic, hypolipidemic, antiarthritic, hypoglycemic and antitumor activity. In this review, we will discuss particularly the largely preclinical use of this agent in the treatment and prevention of cancer. A number of studies have demonstrated the chemopreventive activity of garlic by using different garlic preparations including fresh garlic extract, aged garlic, garlic oil and a number of organosulfur compounds derived from garlic. The chemopreventive activity has been attributed to the presence of organosulfur compounds in garlic. How this is achieved is not fully understood, but several modes of action have been proposed. These include its effect on drug metabolizing enzymes, antioxidant properties and tumor growth inhibition. Most of these studies were carried out in the animal models. Also, recent research has focused on the antimutagenic activity of garlic. Recently, it has been observed that aged garlic extract, but not the fresh garlic extract, exhibited radical scavenging activity. The two major compounds in aged garlic, S-allylcysteine and S-allylmercapto-L-cysteine, had the highest radical scavenging activity. In addition, some organosulfur compounds derived from garlic, including S-allylcysteine, have been found to retard the growth of chemically induced and transplantable tumors in several animal models. Therefore, the consumption of garlic may provide some kind of protection from cancer development.

Altered expression of Na(+)/H(+) exchanger isoforms 1 and 3 in clipped and unclipped kidneys of a 2-kidney-1-clip Goldblatt model of hypertension.

BACKGROUND: Functional differences between the clipped and unclipped kidneys in a 2-kidney-1-clip (2K-1C) hypertension model have been reported. However, the molecular basis of these changes is poorly understood. OBJECTIVES: Expression of NHE-1 and NHE-3 isoforms and sodium pump activity (PNP), and their modulation by blood pressure (BP), PGE(2) and TXB(2) were examined in the kidneys of 2K-1C rats treated with cilazapril for short- (4 and 24 h) and long-term (7 days) periods. METHODS: 2K-1C rats were divided into two groups. Group 1 (short-term) animals were treated with a single dose of cilazapril for 4 or 24 h. Group 2 (long-term) animals received a daily dose of cilazapril for 7 days. 2K-1C animals receiving water served as clipped controls, and sham-operated animals were normal controls. Western blot analysis was used to estimate the protein levels and ELISA for PGE(2) and TXB(2). RESULTS: Levels of NHE-1 and NHE-3 protein in the unclipped kidneys of both treatment groups were increased, whereas levels of alpha-actin, PNP activity and crude microsomes remained unchanged. These changes were significantly reduced by long-term, and not by short-term treatment with cilazapril. In group 1 clipped kidneys, NHE-3 and alpha-actin proteins were increased, and crude microsomes and PNP activity were decreased. In group 2 clipped kidneys, both NHE-1 and 3 isoforms were induced, whereas PNP activity was decreased. Cilazapril did not reverse the changes in the clipped kidneys in both groups, but reduced the crude microsomes. Group 2 unclipped kidneys showed hypertrophy, which remained unaffected by cilazapril treatment. Induced levels of BP, PGE(2) and TXB(2) in both groups were reduced significantly except for the 24-hour post-cilazapril treatment. CONCLUSIONS: These findings demonstrate a differential expression of NHE-1 and NHE-3 isoforms which is dependent on the rise in BP, PGE(2) or TXB(2) in the long-term treatment group, but not in the short-term treatment group. Thus, the changes in NHE isoforms and sodium pump activity, together, contribute to functional differences that exist in the 2K-1C kidneys.