Higher PAR Research Articles

Prognostic and recurrent significance of SII in patients with pancreatic head cancer undergoing pancreaticoduodenectomy.

To investigate the clinical significance of preoperative inflammatory status in patients with pancreatic head carcinoma (PHC), we performed a single-center study to assess it. We studied a total of 164 patients with PHC undergoing PD surgery (with or without allogeneic venous replacement) from January 2018 to April 2022. Systemic immune-inflammation index (SII) was the most important peripheral immune index in predicting the prognosis according to XGBoost analysis. The optimal cutoff value of SII for OS was calculated according to Youden index based on the receiver operating characteristic (ROC) curve and the cohort was divided into Low SII group and High SII group. Demographic, clinical data, laboratory data, follow-up data variables were obtained and compared between the two groups. Kaplan-Meier curves, univariable and multivariable Cox regression models were used to determine the association between preoperative inflammation index, nutritional index and TNM staging system with OS and DFS respectively. The median follow-up time was 16 months (IQR 23), and 41.4% of recurrences occurred within 1 year. The cutoff value of SII was 563, with a sensitivity of 70.3%, and a specificity of 60.7%. Peripheral immune status was different between the two groups. Patients in High SII group had higher PAR, NLR than those in Low SII group (P <0.01, <0.01, respectively), and lower PNI (P <0.01). Kaplan-Meier analysis showed significantly poorer OS and DFS (P < 0.001, <0.001, respectively) in patients with high SII. By using the multivariable Cox regression model, high SII (HR, 2.056; 95% CI, 1.082-3.905, P=0.028) was significant predictor of OS. Of these 68 high-risk patients who recurrence within one year, patients with widespread metastasis had lower SII and worse prognosis (P <0.01). High SII was significantly associated with poor prognosis in patients with PHC. However, in patients who recurrence within one year, SII was lower in patients at TNM stage III. Thus, care needs to be taken to differentiate those high-risk patients.

Photosynthetic mechanism of high yield under an improved wide-narrow row planting pattern in maize

Wide-narrow row maize planting patterns are a popular way to enhance maize yield via improving canopy PAR. To further optimize canopy PAR, we designed an improved wide-narrow row planting pattern (R2) based on the principle of the shortest projection length and the longest illumination of objects on the ground. Compared to the traditional wide-narrow row planting pattern (R1), maize yield increased by about 10% in R2. R2 maize had higher PAR, leaf area index, chlorophyll content, and photosynthetic rates than maize grown in R1. Moreover, compared to maize leaves in R1, the carbon assimilation enzymatic activities were also significantly higher in R2. The higher carbon assimilation enzymatic activity in R2 could account for the increased photosynthetic rate. Thus, the improved wide-narrow row planting pattern could improve photosynthetic performance by enhancing the PAR of the plant canopy, which further promotes the ear number and yield in northeast China.

Effect of Microclimate Modification on Growth and Yield of Pearl Millet

Field experiment was conducted at Agro Climate Research Centre, Tamil Nadu Agricultural University, Coimbatore during the summer 2022 to study the effect of microclimate modification on growth and yield of pearl millet (CO 10). Experiment was laid in Factorized Random Block Design (FRBD) with three factors viz., three levels of land configurations, two levels of mulching and two levels of water stress conditions. Totally 12 treatment combinations that replicated thrice. The results revealed that the paired row with intercropping approach produced the best growth parameters, such as plant height, leaf area index, dry matter accumulation and yield followed by paired row sowing and normal sowing due to higher solar radiation interception and utilization. In terms of irrigation level, maximum growth and yield parameters were observed with 0.75 IW/CPE ratio as compared to 0.5 IW/CPE due to lesser canopy temperature. In respect of mulch treatments, the mulched plots under both the levels of irrigation and at different land configurations had higher DMP and yield by reducing soil moisture stress, lowering the canopy temperature and higher PAR use efficiency It is concluded that the microclimatic alterations through changes in land configuration, irrigation and mulch application showed an effective adaptive strategy to mitigate adverse weather susceptibility and climatic risks in field crops.

Association of Procalcitonin to Albumin Ratio with the Presence and Severity of Sepsis in Neonates.

PurposePrevious studies have demonstrated that procalcitonin and albumin have a close correlation with sepsis. However, the role of procalcitonin (PCT) to albumin (ALB) ratio (PAR) in sepsis was still unclear, especially in neonates. Thus, this study aimed to investigate the association between PAR and neonatal sepsis.Patients and MethodsA total of 1,196 neonates with suspected sepsis were included in this study. Neonates were divided into control group and sepsis group, according to whether they were diagnosed with sepsis. Neonates with sepsis were further divided into mild sepsis and severe sepsis group according to the severity of sepsis. PAR was calculated as serum PCT (ng/mL)/ALB (mg/mL). All statistical analyses were performed using the statistical package SPSS 24.0, as appropriate.ResultsCompared with the control group, neonates with sepsis had a higher PAR. PAR also showed a significant gradual increase in the control, mild sepsis, and severe sepsis groups (P<0.001). Correlation analysis showed that there was a strong positive correlation between PAR and hsCRP, neonatal sequential organ failure assessment score (nSOFA), and prolonged length of hospital stay (P<0.001). On multiple logistic regression, higher PAR was independently associated with the presence and severity of neonatal sepsis. According to the receiver operating characteristic curve analysis, a PAR ≥0.065 had 64% sensitivity and 72% specificity in predicting the presence of neonatal sepsis (area under curve (AUC)=0.72, 95% CI=0.69–0.75, P<0.001) and a PAR≥0.070 had 69% sensitivity and 63% specificity in predicting the presence of severe sepsis (AUC=0.71, 95% CI=0.68–0.74, P<0.001).ConclusionPAR is significantly higher in neonates with sepsis and correlated with the severity of the disease. Increased PAR is an independent predictor useful for identifying the presence and severity of neonatal sepsis.

Altering microclimate of wheat (Triticum aestivum L.) by adjusting sowing dates, irrigation and nitrogen application in semi-arid and arid agroclimatic conditions of Punjab

Field experiments were conducted during rabi seasons of 2017-18 and 2018-19 and results of both the years were pooled to evaluate the microclimate of wheat under five dates of sowing, two nitrogen and two irrigation levels at Ludhiana and Bathinda representing semi-arid and arid agroclimatic regions of Punjab. Soil temperature reported during seed emergence was maximum in early sown (20th October) crop and decreased with delay in sowing at both the locations under study. Canopy temperature from 60 DAS onwards was recorded lower in 5th November and higher in 20th December sown crop while in case of irrigation and nitrogen levels, it was lower under optimal irrigation (I1) and recommended nitrogen (N1) application. Stress degree days (SDD) calculated were also lowest in 5th November sown crop (-323.6oC) and these were lower in N1 (-271.3oC) and I1 (-274.9oC) during both the years, respectively. Better crop growth and hence, leaf area index resulted in higher PAR interception in October sown with optimal irrigation and recommended nitrogen level. Canopy temperature at different periodic intervals (75, 90, 105 and 120 DAS) showed negative correlation with grain yield (R2 = 0.76, 0.75, 0.71 and 0.70, respectively). Similarly, SDD had negative relation with wheat yield (R2 = 0.74).

Response of Nagpur mandarin (Citrus reticulata Blanco) to high density planting systems

High density planting system i.e. accommodating a higher number of plants than routine in a given area is an innovative agro-technology to increase yield and thereby early net returns. Due to conventional wide spacing plantation in Nagpur mandarin (Citrus reticulata Blanco), the land remains unutilized as the plant canopy gradually increases over the years. In the present study, Nagpur mandarin (Citrus reticulata Blanco) budded on Rangpur lime rootstock was evaluated under six different planting spacings. It was observed that the organic carbon (1.10–1.82%) and major nutrients viz. N (309–430 kg ha−1), P (20–54 kg ha−1) and K (291–810 kg ha−1) increased vis-à-vis plant density and was highest under 2 × 2 m spacing. Plants were tallest at 2 × 2 m spacing with the higher PAR interception (88.2) and the lowest leaf area index (1.09). Fruit yield on area basis, under 2 × 2 m spacing was 26, 7.1, 4.6 times more as compared to conventional plantation during the first, second and third year, respectively. At fifth year of crop harvest, the highest B:C ratio (6.36) was recorded in 6 × 3 m followed by 4 × 2 m and 2 × 2 m.

Increased PARylation impacts the DNA methylation process in type 2 diabetes mellitus

BackgroundEpigenetic modifications, such as DNA methylation, can influence the genetic susceptibility to type 2 diabetes mellitus (T2DM) and the progression of the disease. Our previous studies demonstrated that the regulation of the DNA methylation pattern involves the poly(ADP-ribosyl)ation (PARylation) process, a post-translational modification of proteins catalysed by the poly(ADP-ribose) polymerase (PARP) enzymes. Experimental data showed that the hyperactivation of PARylation is associated with impaired glucose metabolism and the development of T2DM. Aims of this case–control study were to investigate the association between PARylation and global and site-specific DNA methylation in T2DM and to evaluate metabolic correlates.ResultsData were collected from 61 subjects affected by T2DM and 48 healthy individuals, recruited as controls. Global levels of poly(ADP-ribose) (PAR, a surrogate of PARP activity), cytosine methylation (5-methylcytosine, 5mC) and de-methylation intermediates 5-hydroxymethylcytosine (5hmC) and 5-formylcytosine (5fC) were determined in peripheral blood cells by ELISA-based methodologies. Site-specific DNA methylation profiling of SOCS3, SREBF1 and TXNIP candidate genes was performed by mass spectrometry-based bisulfite sequencing, methyl-sensitive endonucleases digestion and by DNA immuno-precipitation. T2DM subjects presented higher PAR levels than controls. In T2DM individuals, increased PAR levels were significantly associated with higher HbA1c levels and the accumulation of the de-methylation intermediates 5hmC and 5fC in the genome. In addition, T2DM patients with higher PAR levels showed reduced methylation with increased 5hmC and 5fC levels in specific SOCS3 sites, up-regulated SOCS3 expression compared to both T2DM subjects with low PAR levels and controls.ConclusionsThis study demonstrates the activation of PARylation processes in patients with T2DM, particularly in those with poor glycaemic control. PARylation is linked to dysregulation of DNA methylation pattern via activation of the DNA de-methylation cascade and may be at the basis of the differential gene expression observed in presence of diabetes.

Traditional Vascular Risk Factors Account for Different Proportions of Ischemic Stroke Within Different Gender and Race Groups

Background Few studies have compared the proportion of ischemic strokes attributable to traditional vascular risk factors (population-attributable risk percent or PAR%) between genders and races. The PAR% is a function of the population prevalence and strength of association of a risk factor. Methods A population-based case-control study of ischemic stroke in young adults ages 18-49 in the Baltimore-Washington region was used to study the prevalence, odds ratios, and PAR% of hypertension, diabetes, and smoking among blacks and whites. Logistic regression was used to calculate age-adjusted odds ratios. All analyses were stratified by gender. Results There were 1044 cases and 1099 controls. Of the cases, 47% were black, 54% were women. Roughly a quarter to a third of all strokes in women were attributable to smoking. Due to the higher prevalence of hypertension and a higher odds ratio for hypertension in black men (OR 3.9, 95% CI 2.6-5.9) compared to white men (OR 1.8, 95% CI 1.3-2.6), there was a much higher PAR% for hypertension among black men than white men. See Table 1 for prevalence and Table 2 for PAR% stratified by gender and race. Conclusion Traditional vascular risk factors have the potential to explain a high proportion of ischemic stroke in young adults. The high proportion of strokes in women attributable to smoking underscores the need for targeted smoking cessation interventions in this population. Diabetes and, especially, hypertension are important contributors to the excess population burden of ischemic stroke among blacks. These findings support the value of early screening and treatment for hypertension in young blacks.

Abstract WMP53: Traditional Vascular Risk Factors Account for Different Proportions of Ischemic Stroke Within Different Gender and Race Groups

Introduction: Few studies have compared the proportion of ischemic strokes attributable to traditional vascular risk factors (population-attributable risk percent or PAR%) between genders and races. The PAR% is a function of the population prevalence and strength of association of a risk factor. Methods: A population-based case-control study of ischemic stroke in young adults ages 18-49 in the Baltimore-Washington region was used to study the prevalence, odds ratios, and PAR% of hypertension, diabetes, and smoking among blacks and whites. Logistic regression was used to calculate age-adjusted odds ratios. All analyses were stratified by gender. Results: There were 1044 cases and 1099 controls. Of the cases, 47% were black, 54% were women. Roughly a quarter to a third of all strokes in women were attributable to smoking. Due to the higher prevalence of hypertension and a higher odds ratio for hypertension in black men (OR 3.9, 95% CI 2.6-5.9) compared to white men (OR 1.8, 95% CI 1.3-2.6), there was a much higher PAR% for hypertension among black men than white men. See Table 1 for prevalence and Table 2 for PAR% stratified by gender and race. Conclusion: Traditional vascular risk factors have the potential to explain a high proportion of ischemic stroke in young adults. The high proportion of strokes in women attributable to smoking underscores the need for targeted smoking cessation interventions in this population. Diabetes and, especially, hypertension are important contributors to the excess population burden of ischemic stroke among blacks. These findings support the value of early screening and treatment for hypertension in young blacks.

Utility of Photochemical Traits as Diagnostics of Thermal Tolerance amongst Great Barrier Reef Corals

Light availability is considered a key factor regulating the thermal sensitivity of reef building corals, where excessive excitation of photosystem II (PSII) further exacerbates pressure on photochemical pathways already compromised by heat stress. Coral symbionts acclimate to changes in light availability (photoacclimation) by continually fine-tuning the photochemical operating efficiency of PSII. However, how this process adjusts throughout the warmest months in naturally heat-tolerant or sensitive species is unknown, and whether this influences the capacity to tolerate transient heat stress is untested. We therefore examined the PSII photophysiology of 10 coral species (with known thermal tolerances) from shallow reef environments at Heron Island (Great Barrier Reef, Australia), in spring (October-November, 2015) versus summer (February-March, 2016). Corals were maintained in flow-through aquaria and rapid light curve (RLC) protocols using pulse amplitude modulated (PAM) fluorometry captured changes in the PSII photoacclimation strategy, characterised as the minimum saturating irradiance (Ek), and the extent of photochemical ([1 – C], operating efficiency) versus non-photochemical ([1 – Q]) energy dissipation. Values of Ek across species were >2-fold higher in all coral species in spring, consistent with a climate of higher overall light exposure (i.e. higher PAR from lower cloud cover, rainfall and wind speed) compared with summer. Summer decreases in Ek were combined with a shift towards preferential photochemical quenching in all species. All coral species were subsequently subjected to thermal stress assays. An equivalent temperature-ramping profile of 1°C increase per day and then maintenance at 32°C was applied in each season. Despite the significant seasonal photoacclimation, the species hierarchy of thermal tolerance (maximum quantum yields of PSII (Fv/Fm), monitored at dawn and dusk) did not shift between seasons, except for P. damicornis (faster declines in summer) and Stylophora pistillata (total mortality in spring). Furthermore, the strategy for dealing with light energy (i.e. preferential photochemical versus non-photochemical quenching) was unchanged for thermally tolerant species across seasons, whereas thermally sensitive species switched between preferential [1 – Q] and [1 – C] from spring to summer. We discuss how such traits can potentially be used as diagnostic of thermal tolerance under non-stressed conditions.

Ultraviolet radiation reduces lichen growth rates

We quantified relative growth rates (RGR) in shade-adapted and melanin-deficient thalli of Cetraria islandica and Lobaria pulmonaria cultivated in short-term growth chamber experiments with and without UV-B radiation. In the first experiment done under optimal PAR (125 μmol m−2 s−1), but high UV-B radiation (1 W m−2), UV-B radiation significantly reduced RGR (P < 0.001). The second experiment with higher PAR, but more natural ratios between wavelength ranges (PAR: 500 μmol m−2 s−1; UV-A: 7 W m−2; UV-B: 0.4 W m−2), caused a reduction in mean RGR in L. pulmonaria to just 45% of rates in experiment 1. Lobaria pulmonaria screened from UV-B radiation had 1.9 and 1.6 times higher RGR than non-screened thalli in experiment 1 and 2, respectively. UV-B radiation significantly induced melanin synthesis in the second experiment only, causing significantly less photoinhibition than in thalli receiving just PAR. This is consistent with PAR-protective roles of melanins. Chlorophylls were not affected by UV-B radiation in any experiment. Because UV-B radiation affected RGR more than pure photobiont responses, the mycobiont is likely the more UV-B-susceptible partner. Apart from reduced RGR, we found little evidence for adverse UV-B effects.

Effects of oxygen partial pressure and annealing temperature on the residual stress of hafnium oxide thin-films on silicon using synchrotron-based grazing incidence X-ray diffraction

Synchrotron radiation-based grazing incidence X-ray diffraction (GI-XRD) technique is employed here to estimate the residual stress of < 10nm thin hafnium oxide film deposited on Si (100) substrate at different argon/oxygen ratios using reactive rf sputtering. A decrease in residual stress, tensile in nature, is observed at higher annealing temperature for the samples deposited with increasing argon ratio in the Ar/O2 plasma. The residual stress of the films deposited at higher pAr (Ar:O2=4:1) is also found to be decreased with increasing annealing temperature. But the stress is more or less constant with annealing temperature for the films deposited at lower Ar/O2 (1:4) ratio. All the above phenomena can be explained on the basis of swelling of the interfacial layer and enhanced structural relaxation in the presence of excess Hf in hafnium oxide film during deposition.

Composition control of pulsed laser deposited copper (I) chalcogenide thin films via plasma/Ar interactions

We present how the applied Ar background pressure correlates to the cation and anion composition of Cu(I) chalcogenide thin films grown by pulsed laser deposition (PLD). The as-grown films produced at ∼10−2 mbar pAr show a more pronounced deficiency in lighter composition, as compared with using quasi-vacuum or ∼10−1 mbar. The thermoelectric performance of the as-grown Cu2Se varies consistently with the respective changes in Cu/Se ratio vs. pAr. The optimum thermoelectric performance of Cu2Se is achieved by growing in vacuum or quasi-vacuum, where dense and even thin film morphology is obtained while the cation/anion composition is more congruent than at higher pAr.

Can bottom ice algae tolerate irradiance and temperature changes?

Sea ice algae are significant primary producers of the ice-covered marine environment, growing under typically cold, dim conditions. During ice break-up they are released to the water column, where temperatures can be several degrees higher and irradiance can increase by orders of magnitude. To determine how sea ice algae respond to such rapid changes, we carried out incubations to examine their tolerance to environmentally realistic levels of change in temperature and PAR, as expressed by photosynthetic response and production of mycosporine-like amino acids (MAAs). The algae were also exposed to a broader range of temperatures, to evaluate their potential to function in warmer seas in the event, for instance, of anthropogenic transfer to locations further north. When subjected to PAR (0–100μmolm−2s−1) at ecologically relevant temperatures (−1°C, 2°C, 5°C), the algae showed tolerance, indicated by a lack of decline in the quantum efficiency of photosystem II (PSII). The data show that bottom ice algae can tolerate increasing temperature and PAR comparable to the changes experienced during and after sea ice melt. MAA production increased at higher PAR and temperature. At ambient PAR levels, increased temperatures resulted in lower ϕPSII. However, as PAR levels were increased, higher temperature reduced the level of stress as indicated by higher ϕPSII values. This result suggests, for the first time in sea ice algal studies, that higher temperatures can ameliorate the negative effects of increased PAR. Exposure to much higher temperatures suggested that the algae were capable of retaining some photosynthetic function at water temperatures well above those currently experienced in some of their Antarctic habitats. However, when temperature was gradually increased past 14°C, the photosystems started to become inactivated as indicated by a decrease in quantum yield, suggesting that the algae would not be viable if transferred to lower latitude cold temperate areas.

Porphyromonas Gingivalis is Associated With Protease‐Activated Receptor‐2 Upregulation in Chronic Periodontitis

We previously reported a higher expression of protease-activated receptor-2 (PAR(2)) together with higher interleukin (IL)-1α, IL-6, IL-8, and tumor necrosis factor-α levels, total proteolytic activity, Porphyromonas gingivalis (Pg) prevalence, and neutrophil-protease 3 messenger RNA (mRNA) expression in patients with chronic periodontitis compared to healthy control patients. The aim of the present study is to expand this observation by considering the site level according to the presence of Pg. Microbiologic and gingival crevicular fluid samples were collected from patients with chronic periodontitis. Pg presence was evaluated by polymerase chain reaction and PAR(2) mRNA expression was evaluated by reverse-transcription polymerase chain reaction. Total proteolytic activity in the crevicular fluid was analyzed by using a specific substrate benzoylarginine nitroanilide, and the proinflammatory mediators IL-1α, IL-6, IL-8, and tumor necrosis factor-α were analyzed by enzyme-linked immunosorbent assay. In Pg-positive periodontal sites, the mean probing depth and clinical attachment level, the prevalence of bleeding on probing sites, and crevicular fluid volume were higher (P <0.05) compared to Pg-negative sites. In addition, with the exception of IL-8, all other inflammatory mediators were positively (P <0.05) associated with Pg presence. Pg presence was also positively associated with a higher proteolytic activity (P = 0.0037) and higher PAR(2) mRNA expression (P = 0.0271). We conclude that in chronic periodontitis, periodontal pockets presenting Pg show an upregulation of PAR(2) gene expression, and higher proinflammatory profile associated with advanced clinical destruction, therefore suggesting that Pg plays a pivotal role on PAR(2)-mediated periodontal inflammation in humans.

Establishment and production from thinned mature deciduous-forest silvopastures in Appalachia

Small Appalachian hill farms may benefit economically by expanding grazing lands into some of their under-utilized forested acreages. Our objective was to study the forage production potential of forest to silvopasture conversion. We thinned a white oak dominated mature second growth forested area establishing two orchardgrass-perennial ryegrass-white clover silvopasture replications for comparison with two nearby open pasture replications. After thinning trees, silvopastures were limed, fertilized and seeded. Sheep were fed hay and corn scattered across the area to facilitate removal of residual understory vegetation, disruption of litter layer and incorporation of applied materials into surface soil. Each area was divided into multiple paddocks and rotationally grazed by sheep. Two 1 m2 herbage mass samples were taken from each paddock prior to animal grazing. There was no significant difference in soil moisture between silvopastures and open pastures however, there was adequate rainfall to prevent drought all 3 years. The two silvopastures received 42 and 51% of total daily incident PAR compared to the open field. Total dry forage mass yield from open pasture over the 3 years averaged 11,200 kg ha−1 y−1 and from silvopasture 6,640 kg ha−1 y−1. Silvopastures, however, had a higher PAR use efficiency (PARUE) than open pasture. Hill farms could increase grazing acreages without sacrificing all benefits from trees on the landscape by converting some areas to silvopasture.

Water Level Drawdown Affects Physical and Biogeochemical Properties of Littoral Sediments of a Reservoir and a Natural Lake

ABSTRACT To determine the influence of water level drawdown on littoral areas, we compared the temporal and spatial changes in the water column and sediment in the littoral region of a drinking water reservoir and a natural lake. The reservoir (Sooke) experiences more than six meters of seasonal drawdown compared to a nearby, morphometrically and trophically similar lake (Shawnigan) that experiences less than one meter of drawdown. A greater drawdown in Sooke increased the littoral area and resulted in more littoral water column mixing, more solar warming, and higher PAR at a greater range of littoral depths than in Shawnigan. Based on sediment physical and chemical characteristics, sites farthest from shore were most similar, whereas sites in the drawdown exposure zone of Sooke and the upper littoral area of Shawnigan showed the largest differences. Low macrophyte abundance and loss of fine sediments, nutrients, and organic matter from the drawdown exposure zone in Sooke compared to the equivalent littoral area in Shawnigan suggest that drawdown enhances sediment erosion and focusing. Element and stable isotope ratios of sediment carbon and nitrogen suggest organic matter in the drawdown zone in Sooke is more allochthonous in origin and is coupled more strongly with deeper sites than in Shawnigan. Organic matter source and distribution also suggests that the littoral area extends out farther in Sooke than Shawnigan. This study demonstrates that drawdown has the potential to fundamentally change reservoir littoral sediment and biogeochemical characteristics. Understanding how littoral zones in reservoirs respond to drawdown compared to natural lakes may help water managers make more ecologically informed decisions regarding drawdown impacts on the ecology of littoral zones and water quality.

Orthodontic outcomes assessment using the peer assessment rating index.

The purpose of the present study was to gain more information on the assessment of orthodontic treatment using the PAR Index. The PAR Index was used to assess the study casts of 54 cases treated by 5 orthodontists who successfully completed Phase III of the American Board of Orthodontics. These peer-reviewed cases were considered to represent a subjective opinion of an excellent treatment standard. The PAR scores for the Board-accepted cases were then compared with the PAR scores of 51 cases consecutively treated by orthodontic graduate students. The pretreatment, posttreatment, and percent changes in PAR scores for the Board cases and the graduate student-treated cases were compared. The PAR Index scores and treatment duration were analyzed for the entire sample using general linear models techniques. Results of the study showed no statistically significant difference between the Board-accepted cases and the graduate student-treated cases for any single component of the PAR Index at either the pretreatment or posttreatment times. However, the percent reduction in the mean PAR score for the Board-accepted cases was significantly more than the reduction for the graduate student-treated cases (87.9%+/-9.5% vs 81.7%+/-15.3%). Analysis of treatment duration showed that a higher pretreatment PAR score and a greater percent reduction in PAR score were significantly associated with longer treatment durations.

Influence of water stress on photosynthesis, transpiration, water-use efficiency and yield of Brassica juncea L.

Abstract Indian mustard ( Brassica juncea L. cv. Parkash) grown in large containers was subjected to six watering treatments: (i) no watering after crop establishment; (ii) dry up to floral bud appearance and irrigated thereafter; (iii) dry up to full bloom and irrigated thereafter; (iv) early irrigation, dry during flowering period and irrigated during pod formation; (v) irrigated up to flowering and dry afterwards; (vi) irrigated control. Several plant processes were measured diurnally and seasonally on many clear days. Diurnally, canopy photosynthetic rate (P N ) followed photon flux density (PAR), and transpiration (T) followed air temperature ( T a ). At higher PAR, P N in dry treatments was greater during the first than the second half of the day. Photosynthesis attained compensation point at −4.0 MPa leaf water potential ( Ψ 1 ). Similarly, T during the first half of the day was greater than in the second half of the day at similar T a . Water-use efficiency (WUE) was quite low at high PAR during the second half of the day. Photosynthesis and WUE peaks were observed during the full bloom period while T gradually increased towards maturity. Seed yield was primarily reduced by water stress because of decrease in number of pods per plant and number of seeds per pod. The number of pods per plant and number of seeds per pod were linearly related to seed yield, and cumulative Ψ 1 and P N related to both seed yield and total biomass.

Study of mechanistic features of tetrahedral-octahedral interconversion of tetracyanozincate (II) tobis(4-(2hyphen;Pyridylazo)hyphen;resorcinol)zincate(II) by stopped-flow technique

The present study examines the kinetics and mechanism of the formation of [Zn(CN)4]2− from ZnR22− (R represents 4-(2-Pyridylazo)resorcinol, short named as Par) and vice versa. The reactions have been followed at 494 nm (λmax of [Zn(Par)2]2−, e = 7.8 × 104 M−1 cm−1) using stopped-flow spectrophotometer in presence of excess of incoming ligand. The data show that the formation of [Zn(CN)4]2− complex is first order in [ZnR22−] and the order with respect to [CN−] varies from one at higher cyanide concentration to zero at low [CN−]. These observations suggest a slow dissociation of [ZnR2]2− to ZnR and R2− and a cyanide assisted rapid dissociation of [ZnR2]2− to [ZnR(CN)x]x− followed by their rapid conversion to [Zn(CN)4]2−. The reaction of Zn(Par) with cyanide ions also follow first order kinetics at higher as well as lower cyanide concentrations. The reverse reaction exhibits first order dependence each in [Zn(CN)42−] and [Par2−], but an inverse first order dependence in [CN−] at low Par concentrations. However, at higher Par concentration the reaction rate tends to be independent of [Par2−]. On the basis of forward and reverse rate studies, a five step mechanism consistent with these results has been proposed. The activation parameters and the effect of ionic strength have been used in further support to the proposed mechanism. The effect of pH on the rates of forward and reverse reaction has also been investigated.