High temperature negatively affects cotton production worldwide. In Pakistan, cotton crop faces high temperature at peak flowering during June–July, which is a major reason for yield losses. The present study was conducted to find some agro-physiological markers for high-temperature tolerance. Fifty cotton genotypes were raised under normal sown (high-temperature stress) and late sown (optimum temperature) conditions for 2 years. Data were recorded for relative cell injury percentage (RCI), chlorophyll content (CC), canopy temperature (CT), boll retention percentage (BR), bolls per plant (BP), boll weight (BW), hundred seed weight (HSW), sympodial branches per plant (SBP), plant height (PH) and seed cotton yield (SCY). A large amount of variability was found among cotton genotypes as proved by descriptive statistics. Stable genotypes were selected based on higher SCY and yield components (BP, BW, HSW, SBP, PH and SCY) performance along with less RCI%, high CC and low CT. The results of heatmap analysis showed that the six cotton genotypes viz., FH-Noor, FH-Lalazar, FH-458, FH-466, NIAB-545 and NIAB-878 performed better under high-temperature stress. These selected genotypes can be a source for breeding high-temperature tolerance. Furthermore, the results from correlation analysis confirmed that the traits such as RCI%, CC and CT can be considered as early selection criteria due to their positive association with SCY. Whilst some other parameters such as BP, BW, BR, SBP and PH might be used as direct selection indices for SCY under high-temperature stress.

High levels of stress are expected when crises affect people’s lives. Therefore, this Web-based, cross-sectional study was conducted among university students from Pakistan to investigate the psychological impairment and coping strategies during the coronavirus disease 2019 (COVID-19) pandemic. Google Forms were used to disseminate the online questionnaire to assess anxiety (Generalized Anxiety Disorder-7), depression (Patient Health Questionnaire-9), and coping strategies (Brief-COPE). A total of 1134 responses (age, 21.7 ± 3.5 y) were included. The frequency of students having moderate-severe anxiety and depression (score ≥ 10) were ≈ 34% and 45%, respectively. The respondents’ aged ≥ 31 y had significantly lower depression score than those ≤ 20 y (P = 0.047). Males had significantly less anxiety (6.62 ± 5.70 vs 7.84 ± 5.60; P = 0.001) and depression (8.73 ± 6.84 vs 9.71 ± 7.06; P = 0.031) scores. Those having family members, friends, or acquaintances infected with disease had significantly higher anxiety scores (8.89 ± 5.74 vs 7.09 ± 5.56; P < 0.001). Regarding coping strategies, the majority of respondents were found to have adopted religious/spiritual coping (6.45 ± 1.68) followed by acceptance (5.58 ± 1.65), self-distraction (4.97 ± 1.61), and active coping (4.81 ± 1.57). In conclusion, COVID-19 caused significant impairment on mental health of the students. The most frequent coping strategies adopted by students were religious/spiritual and acceptance coping. During epidemics, mental health of students should not be neglected.

The doped/alloyed HfO2 and ZrO2 thin films revolutionized not only the field of ferroelectric physics but also various ranges of device applications. Especially when the two oxides are combined in an 1:1 ratio, the ferroelectric polarization of the material became the most distinctive. Many researchers have investigated various different process conditions such as controlling Hf0.5Zr0.5O2 (HZO) film thickness and modifying different metal electrodes. Here, we explored the effect of additional Ar plasma treatment to the HZO film. The additional Ar plasma was exposed to the plasma-enhanced atomic layer deposition (PEALD) HZO for this study. Then, the sample was compared with a conventional PEALD and thermal ALD HZO films. By understanding the polarization–electric field (P–E), current–electric field (I–E), and electrical breakdown characteristics of the different samples, it was found that the Ar plasma treatment can control the degree of ferroelectric and antiferroelectric phases of HZO film.

Drought stress negatively affects the cotton production all over the world. The negative impact of drought varies for different species due to some morphological and root attributes that help some species to better stand under drought. But the extent of disturbance varies for different cotton species. To find out such variation, two cotton species (Gossypium hirsutum and Gossypium arboreum) were studied under normal and drought conditions for 2 years. Two genotypes for each species were included, i.e. PC-1 and COMILLA (G. arboreum) and IUB-13 and IUB-65 (G. hirsutum). The experiment was laid out under a completely randomized design following factorial arrangement. Genotype × treatment × year interaction of cotton genotypes was studied for different root, morphological, physiological and fibre-related traits. Traits such as above ground dry biomass, above ground fresh biomass, chlorophyll contents, leaf area, seed cotton yield, sympodial branches/plant, fibre strength and ginning out-turn were higher in G. hirsutum genotypes as compared to G. arboreum genotypes. However less reduction under drought in all above mentioned traits was recorded for G. arboreum, than G. hirsutum. Furthermore, root traits; primary root length, lateral root numbers, root fresh weight and root dry weight were enriched under drought condition in G. arboreum genotypes than in G. hirsutum genotypes, which is a clear manifestation of higher drought tolerance ability in G. arboreum genotypes transferrable to G. hirsutum genotypes through interspecific crossing or other means.

The use of date palm (Phoenix dactylifera L.) has been closely connected with the survival of people in arid areas given their fruits´ high concentration of energy, fibre, minerals, vitamins and 16 amino acids. The arid climate and sandy or clayey loam soils in many parts of Pakistan are ideal for the cultivation of date palm, which contributes to feeding the country's rapidly growing population. To fill knowledge gaps on the effects of cultivar diversity and cultivation sites on the nutritional properties of dates, the present project studied dates and related physical and chemical soil properties across six districts in four provinces of Pakistan: Jhang, Muzaffargarh and Bahawalpur in Punjab; Dera Ismail Khan (D. I. Khan) in Khyber Pakhtunkhwa (KPK); Khairpur in Sindh and Panjgur in Baluchistan. To this end, during 2012–2013, a total of 170 households (HHs) were selected using a snowball sampling approach. Thirty-nine different date palm cultivars with diverse nutritional properties are grown in the study area. In these total soluble solids (TSS) were highest in Muzawati and Koharba cultivars, while cultivars and site conditions significantly affected TSS, minerals (calcium and magnesium), acidity, and firmness of dates. Concentration of CaCO3 and bulk density (BD) of soils varied widely, while hydraulic conductivity (HC) was similar across sites (p = 0.128). Mean soil pH was highest in Panjgur (8.3) and lowest in Muzaffargarh (7.6), soil organic matter content was highest in Jhang (0.8%) and lowest in D. I. Khan (0.6%) and plant available phosphorous (P) was highest in Muzaffargarh (7.8 mg kg−1) and lowest in Panjgur (6.0 mg kg−1). As indicated by correlation analysis BD and cation exchange capacity of soils seemed to affect TSS, whereas concentration of CaCO3 and available P were correlated with calcium concentration of dates. HC and electrical conductivity, however, seemed to have little effect on dates´ nutritional properties.

Multi-robot formation control has become an important area of research due to its advantages and applications. This paper presents multi-robot formation control using a leader–follower approach without considering the leader's velocity information or estimation. The leader–follower formation is formulated by incorporating the model uncertainties and disturbances. A novel formation controller is presented using integral terminal sliding mode (ITSM) control, which drives the formation tracking error convergence to zero in finite-time. The stability of the close-loop control scheme is verified by using Lyapunov theory. Furthermore, obstacle detection and avoidance are incorporated to avoid collision while maintaining the formation. The effectiveness of the proposed controller is verified and validated using sine and lamniscate curve trajectories. Moreover, the performance of the proposed ITSM formation controller is compared with the standard linear sliding mode (LSM) control.

In many parts of Pakistan, availability of green forage is critical to livestock farmers. Forage production is often conducted with two succeeding crops grown within one year and it is highly affected by uncertain availability of irrigation water and low levels of applied mineral fertilisers. The objectives of the present study were to (i) evaluate the effects of crop species, fertiliser type and irrigation level on yield, (ii) determine the corresponding water use efficiency and (iii) investigate relationships between chlorophyll content and crop yield as a basis for a simple sensor-based prediction of crop yield for on-farm use. To this end a two-year field experiment was conducted in Faisalabad, Pakistan, with a completely randomised design with four replications in a split plot arrangement. A combination of fertiliser treatment (control, farm yard manure and mineral fertiliser) and irrigation (recommended irrigation, half recommended irrigation) were assigned to main plot whereas subplots were assigned to cropping systems (common (CCS): Egyptian clover (Trifolium alexandrinum L.) followed by corn (Zea mays L.), drought-adapted (DACS): Oat (Avena sativa L.) followed by Sudangrass (Andropogon sorghum subsp. drummondii). Yield and irrigation water use efficiency of DACS was higher than CCS (14.8 and 26% respectively), the differences were bigger with reduced irrigation and fertilised crops used the available water better than the control. Positive linear relationships were found between chlorophyll concentration estimated by a chlorophyll meter and yield for all crops (r2 = 0.63–0.96), suggesting this technique as a fairly accurate approach to predict yields of crops in vegetative growth stage.

In a field study it was found that application of high P induced Zn deficiency symptoms on onion (Allium cepa L.) plants, increased P concentration but decreased that of Zn. Conversely, application of Zn tended to increase Zn concentration of both tops and bulbs and lowered P concentration. Effectiveness of Zn varied with the amount of P applied. Evidently P and Zn are mutually antagonistic. Using sub-soil on the top of raised beds and heavy P fertilization appear to be responsible for inducing Zn deficiency in onions in northern Nigeria.

The absorption and movement of 14C-labelled maleic hydrazide (2000 mg/1) and 2,4-D (250 mg/1) were studied in seedlings and mature plants of a local strain of onion (Allium cepa L.) from Kano, Nigeria, in the presence and absence of N (20 mg/1).

Plants absorbed and accumulated considerable amounts of both the chemicals. Addition of N to the treatment solution reduced the absorption of 2,4-D. Also, N reduced the mobility of the chemicals from the roots to the tops which resulted in accumulation of the chemicals in the bulbs.

We report on the integration of flowable oxide based Fresnel microlenses with AlGaN based 280 nm light emitting diodes (LED). The lenses were fabricated on the back side of the LED sapphire substrates using direct electron beam writing. Ten concentric rings with different width and variable thickness were designed for 360 degree phase correction. Within each ring the thickness was varied in five steps to approximate a linear profile. The width of each thickness step varied from 100 nm to several microns. Outer diameter of the lens was 65μm. A focal distance of 68 μm was measured for the fabricated microlenses. At the focal plane a FWHM of intensity profile as small as 14 μm was measured for lenses integrated with 30 μm diameter UV LEDs . The maximum intensity at focal plane exceeded the background radiation by a factor of 50. Comparison of the LED performance before and after the lens fabrication did not reveal any degradation of integral efficiency of devices. These results demonstrate the feasibility of using flowable oxide Fresnel microlenses in optical systems based on micro-pixel deep UV AlGaN LEDs.

The evolution of stress during the MOCVD growth of AlN thin films on sapphire substrates under both low and high temperature conditions has been evaluated. The final stress state of the films is assumed to consist of the summation of stresses from three different sources: (1) the stress which arises from residual lattice mismatch between film and substrate i.e. that which persists after partial relaxation by misfit dislocation formation. The extent of relaxation is determined from High Resolution TEM analysis of the substrate/film interface; (2) the stress arising from the coalescence of the 3D islands nucleated in this high mismatch epitaxy process. This requires knowledge of the island sizes just prior to coalescence and this was provided by AFM studies of samples grown under the conditions of interest; and (3) the stress generated during post-growth cooling which arises from the differences in thermal expansion coefficient between AlN and sapphire. The final resultant stress, comprising the summation of stresses arising from these three sources, is found to be tensile in the sample grown at lower temperature and compressive in the sample grown at higher temperature. These results are in general qualitative agreement with results of TEM and High resolution X-ray diffraction (HRXRD) studies, which show evidence for tensile and compressive stresses in the low temperature and high temperature cases, respectively.

In this paper we will describe the problems in growth and fabrication of deep UV LED devices and the approaches that we have used to grow AlGaN-based multiple quantum well deep UV LED structures and to overcome issues of doping efficiency, cracking, and slow growth rates both for the n- and the p-type layers of the device structures. Several innovations in structure growth, device structure design and fabrication and packaging have led to the fabrication of devices with emission from 250-300 nm and cw-milliwatt powers at pump currents of only 20 mA (Vf ≤ 6 V). Record wall plug efficiencies above 1.5 % are now achievable for devices with emission at 280 nm. Thermal management and a proper device design are not only key factors in achieving these record performance numbers but are also crucial to device reliability. We will also discuss some of our initial research to clarify the factors influencing the lifetime of the deep UV LEDs. In addition to our own work, we will review the results from the excellent research carried out at several other laboratories worldwide.

In this paper, we report a study of the degradation of AlGaN-based 280 nm LEDs, which were grown on sapphire substrates using migration-enhanced metalorganic chemical vapor deposition process (MEMOCVD). Electroluminescence (EL), atomic force microscopy (AFM), cathodoluminescence (CL), and scanning electron microscopy (SEM) observations showed that the degradation of deep UV LEDs generally fell into two categories: catastrophic degradation and gradual degradation. The catastrophic degradation was found to be mostly caused by the non-uniformity of surface morphology. The gradual power reduction had two characteristic time constants indicating two possible degradation mechanisms as found from temperature and bias dependent LED power degradation measurements. The faster time constant was bias dependent and virtually constant with temperature whereas the second time constant (slower) varied exponentially with junction temperature. For this temperature dependent part, the activation energies of degradation were determined to be 0.23 eV and 0.27 eV under injected current density of 100 A/cm2 and 200 A/cm2 respectively.